Auxiliary power unit assembly and method of use

ABSTRACT

An auxiliary power unit and a method of providing auxiliary power to a locomotive are disclosed. The auxiliary power unit assembly for a locomotive includes an auxiliary power unit removably coupleable to a rail car chassis. The auxiliary power unit includes a housing, and an auxiliary engine-generator set positioned within the housing. The auxiliary engine-generator set is configured to provide an auxiliary power to the locomotive. The auxiliary power unit also includes an auxiliary controller electrically coupled to the auxiliary engine-generator set. The auxiliary controller is programmed to receive a command and control at least one aspect of the auxiliary power unit in response to the command.

CROSS REFERENCE TO RELATED APPLICATION

The present invention is a continuation of and claims priority of U.S.Provisional Patent Application Ser. No. 61/611,530 filed Mar. 15, 2012,the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

Embodiments of the invention relate generally to auxiliary powerassemblies and, more particularly, to a method and apparatus forproviding auxiliary power to a locomotive.

Traditional railroad locomotives are powered by diesel-electric powersources, where a diesel engine drives a generator to produce electricpower. The output power produced by these engine-generator sets is inturn used to power one or more electric traction motors. The tractionmotors power the drive wheels of the locomotive.

Locomotives are, by nature, self-contained in that they generate and usethe power they require. Typically, locomotive limits are defined by theequipment and fuel that can be carried on the locomotive chassis.Attempts have been made to extend locomotive limits by, for example,attaching a tank car containing fuel (or water) behind a locomotive togive it extended operating range. However, these approaches are oflimited utility and are generally not practiced due to harsh operatingconditions that limit the ability to distribute locomotive functionsacross disparate chassis as well as the technical challenges ofintegrating stock railroad equipment with locomotives.

In recent years, as power needs have grown and railroads have becomemore concerned about emissions and fuel costs, a variety of approacheshave been tried to improve the efficiency of locomotive power.

One such approach is a genset diesel locomotive, which includes acomputer-controlled system that manages multiple smaller diesel enginesthat are turned on and off as power requirements of the railroadlocomotive varies.

FIG. 1 illustrates a schematic of an exemplary prior art genset diesellocomotive 10 that includes a locomotive controller 12 that managesmultiple engines and additional sensors and inputs. Genset diesellocomotive 10 includes a first engine-generator set 14 and a secondengine-generator set 16, both operating in response to locomotivecontroller 12. Each engine-generator set 14, 16 includes an engine 18,20 connected to a respective generator 22, 24, which produce electricityfor the locomotive traction bus 26 and an auxiliary power bus (notshown). Generators 22, 24 are configured to convert the mechanicalenergy provided by engines 18, 20 into a form acceptable to one or moretraction motors 28 (DC or AC type) configured to drive the axles coupledto the driving wheels 30 of the locomotive 10, and to provide DC or ACpower to the respective auxiliary power bus. The amount of powerproduced by each generator 22, 24 is determined by the engine RPMs andthe generator excitation control inputs that are received by generators22, 24 from locomotive controller 12.

The computer-controlled system for a typical genset diesel locomotiveincludes an analog electro-mechanical locomotive controller 12 with athrottle control electro-mechanically linked to the controller 12. Thecontroller 12 controls the amount of power generated by theengine-generator sets 14, 16 by varying engine speed and generatorexcitement in order to produce the desired amount of power on thetraction bus 26. In some of these control systems, additional powersensors (not shown), such as load regulators, are used to monitor thefraction bus 26 and/or one or more traction motors 28 and provide inputto the controller 12 so it may more accurately manage theengine-generator sets 14, 16. Specifically, the control system usesthese sensors for feedback to further govern control of the amount ofpower generated by the engine-generator sets 14, 16.

Locomotive 10 also includes an engine start and stop control 32 whichinterfaces with the locomotive controller 12 and is linked toengine-generator sets 14, 16 to initiate their operation and toterminate their operation.

Locomotive 10 also includes engine sensors 34, 36 electrically coupledto engines 18, 20 and the locomotive controller 12. Engine sensors 34,36 transmit signals 38 to the locomotive controller 12 regarding thestatus and/or operation of each of the engines 18, 20 (e.g., variousparameters of the engines 18, 20 such as RPMs, operating power output,temperature, and other engine status or operating parameters).Locomotive controller 12 transmits control signals 40, including engineRPM settings, generator excitation control inputs, etc., toengine-generator sets 14, 16 to control operation thereof.

In some implementations, engines 18, 20 are operated in response to athrottle position input sensor 42 which indicates the position of thethrottle as controlled by the operator at an operator interface 44. Inaddition, an operator engine start input 46 may be included where theoperator can directly or indirectly instruct the locomotive controller12 (e.g., via a keypad (not shown) located on operator interface 44)with regard to initiation of operation of the engines 18, 20 ortermination of operation of the engines 18, 20.

The second to second operation of a locomotive is managed by locomotivecontrollers. In general, there are two types of locomotive controllers,“traditional” controllers that recognize and control a singleengine-generator combination installed on the locomotive chassis, and“genset” controllers, which control a plurality of engine-generatorcombinations installed on a locomotive chassis. These locomotivecontrollers manage the production of electricity, provision of theelectricity to the power bus, and the generation of tractive effort bytraction motors that use the provided electricity. These locomotivecontrollers also manage fuel use and efficiency, emissions production,and other aspects of the locomotive operation.

In each of these cases, the locomotive controller manages a static,predefined arrangement of one or more engine/generators that providepower to a bus, which in turn provides power to traction motors thatmove the locomotive. Some locomotive controllers have been configured tocontrol static arrangements of dissimilar power sources (such as anengine-generator, fuel cell, gas turbine, or batteries). These staticarrangements have failed due to the lack of operational flexibilityrequired for day-to-day operation of locomotives and/or operationallimitations (such as locomotive range, power production limitations, andrequiring support for multiple fuel sources). In particular, “genset”style locomotive controllers have not found use in line haulapplications because they produce lower overall power than a single,large engine. The amount of power available to the traction motors is akey operational component that characterizes line haul locomotives. Useof dissimilar power source arrangements have failed due cost andoperational issues.

Known locomotive controllers also fail to address unexpected signals andoperational challenges that become evident when extending the locomotivecontrol and power systems between disparate railcar chassis andintegrating power from these external sources with power produced by theengine/generator(s) on the locomotive chassis. As a result, manylocomotive power tender configurations have been tried and abandoned dueto a number of operational, safety, and related technical issues.

Operational and safety concerns of extended locomotive control and powersystems are many and varied. First, locomotive controllers and powertenders may be some distance apart, particularly in consists in whichmultiple power tenders are utilized. Each rail car is approximately 100feet in length, and signal degradation, electro-magnetic interference,propagation delays, and related issues are factors when operating apower tender and locomotive together.

Second, extending the power bus (sometimes called a fraction bus)between railcars presents similar concerns, not with the signaldegradation, but with the cabling and switching apparatus used to safelytransport high amperage currents (e.g., 2000 amps) between the powertender and the locomotive fraction bus. Power losses, in particular,voltage losses, arcing, and related issues come into play. Sincelocomotive power blending is governed by the voltage of the providedpower, and is characterized by tight control of the voltage provided tothe power bus, losses in voltage or current between a power tender andthe locomotive will cause the locomotive controller to improperly managethe combined locomotive/tender. In some cases, these losses will causethe locomotive to not operate. Switching of high amperage power requiresSpecialty circuitry is also need when switching high amperage power toprevent arcing, contact welding, voltage and amperage spikes and drops,etc.

Third, locomotives and attached power tenders operate in harshenvironments. These environments include physical and electro-magneticchallenges. The physical challenges are many and varied; they includewidely varied operating temperatures, weather, poor electricalconnections between the locomotive and the tender, etc. The control andsensor data is subject to intense electro-magnetic environments (thatdisrupts the control and sensor data) both external to the consist andwithin the infrastructure. The shielding required to mitigate theseissues described above is itself susceptible to the physical challenges,and degrades over time. Operating a locomotive/power tender in theseconditions is challenging.

Fourth, locomotives and their attached power tenders may encounteroperational issues, such as connector failure, cable separation, or evenchassis separation during regular operation (for example, as would becaused by a coupler failure). Both the locomotive and the attached powertender must safely operate when these conditions occur.

To understand these issues, one must consider both physical and logicalconstraints of current locomotive consists and locomotive controllerarchitecture.

Railroads have operated many configurations of locomotives and powertenders over the years. Traditionally, locomotive arrangements (hereincalled a “consist”) include multiple locomotives, linked together usingmultiple-unit (“MU”) controls. A locomotive consist is the arrangementof locomotives, slugs, and power tenders which are coupled together toprovide motive power to a train. One common arrangement is the couplingof two or more independent locomotives together and operating them as asingle unit. This arrangement of locomotives has an independentlocomotive controller for each locomotive chassis, and shares onlythrottle setting (an input to a locomotive controller), brake settings,and fault indications. These throttle settings, brake settings, andfault indications are communicated using combination electrical andpneumatic connection commonly referred to “multiple unit” (“MU”).

MU locomotive arrangements are the current operating paradigm for mostrailroads today. MU locomotives arrangements are characterized by eachlocomotive having its own independent power generation, distribution(bus), and traction motors. MU controls relay throttle and brakeinstructions from a first locomotive (master or “A” units) to one ormore second locomotives (slaves or “B” units), where these instructionsare independently interpreted and tractive effort is providedindependently by each locomotive in the consist.

MU locomotives operate independently and do not share power or enginecontrol signals, nor do they permit a first locomotive controller tomake requests of a second locomotive controller. Similarly, thelocomotive controllers of locomotives operating in MU fashion do notshare operational data and do not make operational decisions about theoperations of a first locomotive controller based upon the operationalcharacteristics of the second locomotive controller.

Locomotive controllers can be generally characterized as outputtingengine control voltages (e.g., RPM and generator excitement voltages),receiving sensor input of operational information (e.g., actual RPM,some fault information, and, in some cases, power bus sensor readings),and then acting to adjust the operation of the engine by varying itscontrol voltages. Locomotive controllers manage the locomotives enginesand provide power blending by controlling the amount of power andvoltage provided by each engine to the common power bus, which permitsthe provided power to be combined on the power bus.

Known locomotive controllers are constructed with a basic assumptionthat the power sources that they control are provided in a fixedarrangement. If a locomotive controller is unaware of multiple possiblepower sources (e.g., a traditional controller described above), then theuse of an external power tender can only be provided on an “all ornothing” basis, where the power tender directly substitutes for theengine-generator on the locomotive chassis. Given the complex nature oflocomotive control and the interrelatedness of locomotive loads such astraction motors and blowers, a locomotive's controller, itsengine-generator, and an external power tender cannot “share” thegeneration requirement, with a portion of the power coming from theengine-generator, and remainder of the power coming from the externalpower tender without the locomotive controller being aware of the powertender and the amount of power it produces. The locomotive controllerwill recognize the additional power available on the bus and eitherfault, mis-control one or more power sources or loads, or even turn offthe locomotive's engine-generator. Since other locomotive systems areoften tied to the locomotive engine-generator or are utilizedproportionally to the amount of power being used by locomotives loads(e.g., blowers, aux power), this results in a non-functioninglocomotive.

Specialty locomotive controllers that are aware of multiple powersources also have challenges operating with external power tenders.First, the locomotive controller must be able to handle “powerblending,” simultaneously taking part of the required power from a firstpower source and taking a second part of the required power from asecond power source. Specialty controllers that select between one powersource or another have the same operational challenges as a traditionallocomotive controller (described above). Also, specialty controllershave the operational constraints of each specialty power sourcehard-coded into their logic and electronics, making changes to the powersource configuration hard to impossible.

“Genset” style locomotive controllers are characterized in that they aredesigned to control multiple engine-generators and to “blend” the powerproduced by these generators. “Genset” style locomotive controllerstypically operate in the DC realm, where they set the power sources toproduce differing power amounts at differing voltages, as the blendingof power on a common bus is based upon voltage differentials between thepower bus and the various power sources (e.g., onboardengine-generators, power tenders). As voltage on the bus drops underload, additional power flows from power sources providing power atvoltages about the power bus voltage. Thus, tight voltage control mustbe used to operate correctly.

Each diesel engine-generator combination is controlled with one set ofoperational parameters and is controlled by varying run RPM andalternator excitement. Even when engines are placed on disparate railcarchassis, a genset locomotive controller expects that the power tenderprovides a static, well-known power source that behaves as if it werepresent on the locomotive chassis. Genset locomotive controllers do notaccount for the operational issues described above, which lead tono-power, under-power (power not flowing from the power tender to thelocomotive power bus), or even whether the power tender is currentlyattached as part of the consist.

Additionally, genset controllers have built-in assumptions regarding thepower curve and engine settings (e.g., RPM, generator excitement) thatare used to produce specific power/voltages. These operating assumptionsare violated by physical limitations induced by separating the powertender from the locomotive chassis (as described above), and by logicalconsiderations that power tenders may have differ operating parametersand settings (e.g., differing engine type, characteristics, fuels). Incurrent configurations, power tenders and locomotive controllers must beoperated as a single, non-varying consist because of inherentlimitations in the locomotive control and the lack of locomotivecontroller knowledge of differing power tenders and each power tendersinstructions and operational characteristics.

Newer locomotive power control systems have evolved fromelectro-mechanical to digital controls offering a variety of new optionsfor power control that perform the same functions as the olderelectro-mechanical control systems, as well as add new power managementand train control functions in order to improve performance and fuelefficiency. However, retrofitting these digital controllers topre-existing (legacy) locomotives is problematic.

The cost and technical integration challenges of replacing an existinglocomotive control system of these older legacy locomotives with a newgeneration control system are prohibitive. Generally, this requires thewholesale replacement of the locomotive control system and many of thelocomotive controls, as well as substantial modifications to thelocomotive engine, generator, and other electrical components on thelocomotive. Furthermore, these types of changes typically cause areclassification of the locomotive and require recertification of thelocomotive power plant for safety and emissions. The recertificationprocess requires that the engine emissions be updated to current EPArequirements, which adds additional cost. Combined, these costs areprohibitive.

In response to rising fuel costs and tightening emissions controls,attempts have been made to provide alternative power sources for gensetdiesel locomotives, including replacing the diesel fuel and engine withhydrogen and natural gas powered engines, fuel cells, batteries, andother mechanisms for generating and storing power. While in theory thesealternative fuels are capable of producing traction power at a fractionof the cost of a diesel locomotive engine/generator, the use of thesealternative power sources pose several challenges for the locomotiveindustry.

For example, outfitting railroad locomotives with alternative fueltechnology incurs expensive infrastructure costs and fueling times.Gaseous fuels, such as hydrogen and natural gas, provide limited range,have limited stored energy, have long refueling times, and requireextensive alternative fueling infrastructures. While attempts have beenmade to add alternative power sources and fuel sources to the locomotiveconsist, the power and fuel sources are provided in heavy railcontainers that require large, container-handling cranes in a rail yardin order to lift containers that house engines and their alternativefuel sources, thereby limiting refueling of alternative fuel locomotivesto rail yard locations that support the alternative fuel infrastructure.Further, expensive, rail yard based infrastructure, such as extensivecascades of pressurized tanks are needed to refuel a single set oflocomotive tanks. These expensive rail yard infrastructures make the useof these existing technologies untenable. Still further, manyalternative locomotive power approaches add substantial amounts of timeto refueling and other maintenance operations. For example, the timerequired to refuel a set of tanks of natural gas is measured in hours,where the time required for fueling a diesel locomotive is closer tofifteen minutes. Fueling times further restrict alternative fuel uses toyard applications such as switchers where the alternative fuel equipmenthas substantial time available for recharging.

Existing systems also do not recognize the fundamental cost improvementfor railroad locomotives that is available is based upon the cost offuel relative to the amount of energy that is produced by using thatfuel, and that other optimizations often are minor in comparison. Thesesystems also fail to recognize that different fuels have differentenergy content, and that these fuels have different costs depending uponwhere they are obtained. For example, diesel fuel typically costs morein California than it does on the Gulf Coast, and depending upon marketconditions, it may be more efficient to use natural gas, syngas, processgas, diesel, or some other fuel to produce the power required forrailroad locomotive use. For these and other reasons, alternativefuel-based power for railroad locomotives has not been accepted by theindustry.

Further, retrofitting pre-existing (legacy) locomotive enginecontrollers for use with alternative fuels is generally cost prohibitiveand bring concerns about reliability in these retrofit applications.Current railroad locomotive inventories include many thousands of olderlocomotives, such as the EMD SD-40 family. The control systemsintegrated into these pre-existing legacy locomotives typically employ asingle engine/generator combination that is controlled withelectro-mechanical or simple electronic control systems. The lack offlexibility of these older control systems prohibits the use of newer,more desirable, power sources capable of operating with alternative fuelsources.

In light of the above, it would be advantageous to maintain the abilityto operate an existing locomotive engine using the fuel for which it wasoriginally designed while adding the ability provide extra power to thatlocomotive from an auxiliary power source. Such an approach would allowfull redundancy of power generation from more than one fuel andengine/generator, and may in certain situations, allow a controller toprovide power to the wheels of more than 100% of the locomotiveengine/generator set originally paired with the drive motors.

In light of the above, it would be desirable to design an apparatus andmethod for providing an auxiliary power source for a locomotive that canbe integrated with existing electro-mechanical locomotive controls toprovide the benefits of being able to incorporate power from alternativefuel sources with a minimum of rework or recertification of thelocomotive power plant or other locomotive systems, such as fans, airconditioning, or additional sensors.

It would further be desirable to design an apparatus and method forrefueling a locomotive that permits the use of alternative fuels in easyto use interchangeable delivery systems, where alternatives, such ascurrently available gaseous fuels, can be provided to railroadlocomotives without incurring expensive infrastructure costs and fuelingtimes.

It would also be desirable to design a railroad locomotive thatoptimizes power usage based upon the costs of available fuel and powerrequirements, permitting fuel- and power-cost arbitrage within thelocomotive and substantially reducing the costs of operating thelocomotive.

BRIEF DESCRIPTION OF THE INVENTION

Embodiments of the invention overcome the aforementioned drawbacks byproviding for the use of alternative fuel-based power for railroadlocomotives, enable the use of situationally available fuels to powerrailroad locomotives, and permit railroad locomotives to makecost-advantaged use of alternative power when it is cost effective to doso.

In accordance with one aspect of the invention, an auxiliary power unitassembly for a locomotive includes an auxiliary power unit removablycoupleable to a rail car chassis. The auxiliary power unit includes ahousing, and an auxiliary engine-generator set positioned within thehousing. The auxiliary engine-generator set is configured to provide anauxiliary power to the locomotive. The auxiliary power unit alsoincludes an auxiliary controller electrically coupled to the auxiliaryengine-generator set. The auxiliary controller is programmed to receivea command and control at least one aspect of the auxiliary power unit inresponse to the command.

In accordance with another aspect of the invention, a locomotiveassembly includes a locomotive having a power bus, a primaryengine-generator set electrically coupled to the power bus, and alocomotive controller programmed to control the primary engine-generatorset. The locomotive assembly further includes a first power unit havinga first auxiliary engine-generator set electrically coupled to thelocomotive power bus and a first auxiliary controller. The firstauxiliary controller is programmed to receive a command signal from thelocomotive controller indicating a desired amount of power, and controlthe first auxiliary engine-generator set to produce the desired amountof power.

In accordance with yet another aspect of the invention, a method ofproviding auxiliary power by an auxiliary power unit includes couplingthe auxiliary power unit to a power bus of the locomotive, where theauxiliary power unit includes an auxiliary engine-generator set and anauxiliary controller electrically coupled to the auxiliaryengine-generator set. The method also includes coupling the auxiliarycontroller to a primary locomotive controller, receiving a power commandfrom the primary locomotive controller in the auxiliary controller, andcontrolling the auxiliary engine-generator set to generate an auxiliarypower for delivery to a power bus of the locomotive responsive to thepower command.

These and other advantages and features will be more readily understoodfrom the following detailed description of preferred embodiments of theinvention that is provided in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate preferred embodiments presently contemplated forcarrying out the invention.

In the drawings:

FIG. 1 is a schematic diagram of an exemplary prior art diesel gensetlocomotive.

FIG. 2 is a schematic diagram of an auxiliary power unit assembly, inaccordance with an embodiment of the invention.

FIG. 3 is a schematic diagram of an auxiliary power unit, in accordancewith an embodiment of the invention.

FIG. 4 is a schematic diagram of a locomotive assembly including agenset locomotive and the auxiliary power unit assembly of FIG. 2, inaccordance with an embodiment of the invention.

FIG. 5 is a schematic diagram of a gaseous fuel assembly, in accordancewith an embodiment of the invention.

FIG. 6 is a schematic diagram of a fuel assembly manager for the gaseousfuel assembly of FIG. 5, in accordance with an embodiment of theinvention.

FIG. 7 is a schematic diagram of a pressure tank assembly, in accordancewith an embodiment of the invention.

FIG. 8 is a schematic diagram of a gaseous genset locomotiveincorporating the gaseous fuel assembly of FIG. 5, in accordance with anembodiment of the invention.

DETAILED DESCRIPTION

Auxiliary power arrangements set forth herein permit the provision ofadditional power to a locomotive over the amount of power that can beproduced by the engine/generator combination(s) that are part of thediesel locomotive. In some operational situations, such as when thelocomotive consist is running at higher speeds, the pulling capacity ofthe locomotive is limited by the amount of power that can be provided bythe locomotives to their traction motors. The use auxiliary powerpermits the locomotive to move the train to greater speeds.

Embodiments of the described systems and methods also support theconcept of power arbitrage between differently fueled locomotive powersources, where the arbitrage is made based upon cost of fuel or the costof delivered power vs. the power needs of locomotive traction andauxiliary loads.

Still further, embodiments of the described systems and methods enable ametering-based power delivery approach, where the locomotive power usefrom alternative fuel power sources is metered and may be separatelyinvoiced or billed to the railroad or locomotive operator. While thesystems and methods of use set forth herein are described as being usedin connection with the locomotive industry, one skilled in the art willrecognize that the benefits of the fuel assembly, rail car assembly, andmethod for providing fuel are equally applicable to any number ofalternative industrial applications in which a fuel tank is coupled toan engine, such as, for example, in the trucking industry or themaritime industry.

One key aspect when using alternative fuel types in a power tender isthe differential in fuel cost, or ultimately, the cost of a unit ofpower provided to a power bus. The locomotive controllers set forthherein are able to arbitrage fuel and power costs between thelocomotive's power sources and auxiliary power units provided in a powertender to more efficiently operate. Further, the locomotive controllersand auxiliary power units set forth herein are able to communicateadditional information (such as its ID, control input description,control settings/emissions, control setting/generated power graphs, fueltype, power cost) about the control and operation of the auxiliary powerunit to the locomotive controller. Absent at least some of thisinformation, the locomotive controller would be unable to effectivelycontrol the auxiliary power units.

A locomotive consist is defined for purposes herein as an arrangement oflocomotives and auxiliary power units, coupled together, which sharecontrol and power connections between at least one locomotive and atleast one auxiliary power unit. For purposes of illustration, severalexemplary configurations of consists may be defined as follows:

A-B Consist: One locomotive coupled to one auxiliary power unit. Theauxiliary power unit provides at least some, but not all, of theelectrical power required by the locomotive.

A-B-A Consist: Multiple locomotives are coupled to one auxiliary powerunit. The auxiliary power unit provides a least some, but not all, ofthe electrical power required by each of the locomotives.

A-B-B Consist: One locomotive is coupled to multiple auxiliary powerunits. The auxiliary power units together provide at least some of theelectrical power required by the locomotive.

Referring now to FIG. 2, an intermodal container-mounted auxiliary powerunit assembly 48, is illustrated in accordance with an embodiment of theinvention. Auxiliary power unit assembly 48 includes an auxiliary powerunit (“APU”) 50 that is designed to interface with one or morelocomotives, such as genset diesel locomotive 10 of FIG. 1 and one ormore interchangeable gaseous fuel assemblies 52, as described in moredetail with respect to FIGS. 6-7. As described in detail below, APU 50provides additional power to the connected locomotive(s) in the consistunder direction of at least one primary locomotive controller. As usedherein, the term “auxiliary power unit” or “APU” is used to refer to anautonomously controlled device capable of generating and supplyingauxiliary power to a locomotive. The term “autonomous,” as used herein,refers to an APU that able to act independently and control the internaloperations of the APU independent of external requests, and wherein theinternal workings of the APU are opaque or unknown to external controlsystems.

According to various embodiments, APU 50 is capable of employing one ormore alternative fuels. As shown, APU 50 is provided within a container54 that is fastened to a tender car or rail car 56 in a manner thatsecures container 54 to the rail car 56. In one embodiment, container 54is a modified intermodal container and rail car 56 is adapted forcarriage of intermodal containers. Providing APU 50 within a removable,intermodal container 54 permits APU 50 to be swapped in and out ofservice quickly for maintenance and overall at any rail yard that hascontainer lift capability. A ground path is provided between thecontainer 54 and ground via rail car 56, its wheels 58, and the track(not shown). This provides for the dissipation of any static chargesthat may build up. The system for fastening container 54 to the rail car56 may have shock isolation features to reduce the severity of shockevents that occur in normal railroad operation from APU 50.

As shown, auxiliary power unit assembly 48 includes one or more fuelassemblies 52 stacked atop the container 54 housing APU 50. Fuelassemblies 52, which include pressure tanks 60 housing fuel, areinterconnected with APU 50 to deliver fuel to APU 50 under the controlof APU 50, as described in more detail below. In the embodiment shown inFIG. 2, fuel assembly managers 62 of fuel assemblies 52 are incorporatedwithin respective frames 152 of fuel assemblies 52 as described withrespect to FIG. 6. In an alternative embodiment, fuel assembly manager62 can be incorporated within the container 54 of APU 50.

A schematic block diagram of APU 50 is illustrated in FIG. 3. APU 50includes a number of fuel assembly interfaces 64 for fluidly couplingAPU 50 to fuel assemblies 52. While two fuel assembly interfaces 64 areillustrated in FIG. 3, one skilled in the art will recognize that APU 50may be constructed having only one fuel assembly interface or more thantwo fuel assembly interfaces to connect any number of fuel assembliesthereto. Each fuel assembly interface 64 includes a respective fuelinlet 66 fluidly coupled to an electronically controlled valve 68, suchas, for example a solenoid or other common, remotely actuated highpressure valves. These valves may optionally be integrated as part ofthe fuel inlet 66. Each fuel assembly interface 64 may include adedicated control interface to permit an APU controller 70 tocommunicate with each connected fuel assembly 52. Alternatively, fuelassembly interface 64 may be connected to a common control interface 72of APU 50. According to one embodiment, fuel inlet 66 is an industrystandard fuel connector such as, for example, the GMV-09 receptacleprovided by Staubli. Fuel assembly interface 64 may also include anoptional power interface to the fuel assembly (not shown for clarity).Additional input fuel sensors (not shown) (e.g., flow, pressure,temperature) may be added to each fuel interface 64 as desired.Electrical connectors (not shown) may be provided to the control andpower interfaces so a fuel assembly may be quickly removed and replaced.

Each fuel inlet 66 is fluidly connected to its respective controlledvalve 68, which is in turn connected to a fuel manifold 74. Fuelmanifold 74 may optionally further comprise a mixing chamber 76 (shownin phantom) in which fuels from one fuel assembly 52 may be mixed with afuel from another fuel assembly 52. Suitable flow regulation and safetyvalves may be provided (not shown) to prevent fuels from mixing upstreamof a mixing chamber 76. In addition, fuel conditioning equipment such asexpansion and fuel routing valves described with respect to fuelassembly 52 in FIG. 6 may be included in manifold 74. APU controller 70is also electronically connected with the solenoid controlled valves andthe manifold controls, which enables it to control the delivery ofgaseous fuels to APU engine 78. The manifold 74 routes the resultinggaseous fuel through a pressure regulator 80, which is fluidly connectedto APU engine 78. Pressure regulator 80 may optionally be controlled byAPU controller 70, depending upon the fuel input demand of the APUengine 78.

APU controller 70 may also be electrically connected to fuel assemblymanagers 62 of each connected gaseous fuel assembly 52, either via thecommon control interface 72 or via a dedicated control interfaceassociated with the fuel assembly interface 64. APU controller 70interacts with fuel assembly managers 62 to receive fuel information andto provide instructions for configuring the gaseous fuel state required.

Auxiliary power unit 50 includes an auxiliary engine-generator set 82having an engine 78 and a generator 84. According to variousembodiments, engine 78 is an internal combustion engine configured toburn a gaseous fuel, such as, for example, a modified diesel, aspark-combustion engine, a radial engine, a gas turbine, and the like.Engine 78 is electrically connected to APU controller 70 to permit APUcontroller 70 to set engine operating parameters in order to optimizeengine performance on the current fuel in use and requested powersetting. These engine parameters may include throttle settings (settingfor engine RPM), ignition timing settings (for changing combustiontiming for different gaseous fuels), combustor settings (for gasturbines), and the like. Engine sensors (not shown for clarity) may beintegrated with APU 50 in order to detect the performance of the engineand provide inputs to APU controller 70. These sensors may include anRPM sensor that determines the actual engine RPM, exhaust sensors thatdetermine the composition and/or temperature of exhaust gasses, enginetemperature, and engine fault sensors. Other engine control sensors maybe added to APU 50 without deviating from the design.

Engine 78 is mechanically connected to generator 84, which converts themechanical output of engine 78 to electrical energy. Generator 84 iselectrically connected to APU controller 70 in order to permit APUcontroller 70 to control aspects of the electrical generation. APUcontroller 70 may control generator inputs such as polarity, phase,amount of excitement, desired voltage, shunting, and the like. Optionalsensors (not shown) may be connected to the output of generator 84 tomeasure the output of generator 84 and provide feedback to APUcontroller 70. According to various embodiments, generator 84 mayinclude special circuitry to cause generator 84 to more quickly react tocontrol inputs that reduce the amount of power being produced. Thiscircuitry reduces the “electrical inertia” of generator 84, effectivelypermitting the generator output to more quickly match the amount ofelectrical power that it is instructed to produce. One such method ofreducing the electrical inertia of generator 84 is to provide a switchedresistor that is used to quickly drop the excitation current in thegenerator. Another such method is to provide a means to dampen thequickly dampen the excitation field of generator 84 by activating asolenoid controlled shunt across the excitation coils of generator 84.Either method may be controlled by APU controller 70, or may beintegrated with generator 84 in a manner so that they automatically areused when the amount of excitation requested is substantially reduced.

As shown in FIG. 3, generator 84 is electrically connected to at leastone electrical manager 86, which manages the electricity generated byAPU 50 and provides that electricity to a specific locomotive. When APU50 is connected to more than one locomotive at a time, multipleelectrical managers (one per connected locomotive) may be used in orderto electrically isolate each locomotive. Electrical isolation supportsautonomous fault management by APU 50 and enables providing differingamounts of power to each locomotive (e.g., a first locomotive requestsand receives 1 MW, the second locomotive requests and receives 200 kW ofpower).

According to various embodiments, electrical manager 86 furthercomprises one or more of a controllable switch 88, a regulator 90, ameter 92, and a power interface 94. Power is routed from the generator84 thru controllable switch 88 and regulator 90, then optionally thrumeter 92, and finally to power interface 94. Controllable switch 88 andregulator 90 may be implemented as discrete devices, or may beoptionally integrated into a single device. The order in whichcontrollable switch 88 and regulator 90 are operated inline isimplementation dependent, and either component being first in order maybe performed without deviating from the invention. Controllable switch88 enables and disables power flow from auxiliary power unit 50 to alocomotive. Controllable switch 88 may be implemented using either ahigh amperage switch or relay, or as one or more high power siliconswitching module. Regulator 90 limits the amount of power flow betweenAPU 50 and the locomotive to an amount specified by APU controller 70.Meter 92 measures the amount of power actually delivered to thelocomotive.

Power interface 94 is configured so that it may be electrically coupledto either or both of traction and auxiliary power busses on alocomotive, as described in more detail with respect to FIG. 4. In oneembodiment, the coupling between power interface 94 and the locomotivetraction and/or auxiliary power buses is made using cables of a size andconstruction to handle the anticipated power transmission. The cablesare equipped with connectors that permit quick connection anddisconnection of the cables from the power interface and the locomotivepower bus(es).

Electrical manager 86 further comprises one or more fault sensors 96which detect problems with the transmission of electrical power to thelocomotive. Examples of faults may include ground short, high voltage,low voltage, high current, low current, over temperature, and connectordisconnect. Additional fault sensors may be integrated into APU 50 basedon design specifications. A single fault sensor may be provided thatprovides all of the fault detection of fault sensor 96, or the faultsensor may be built of a number of discrete sensors.

Each of these components 88, 90, 92, 94, 96 of electrical manager 86 iselectrically connected to APU controller 70, so that APU controller 70may receive input and configure the operation of each aspect ofelectrical manager 86 in order to provide the requested amount of powerto the locomotive that is electrically connected to each electricalmanager 86. Connection may be directly to APU controller 70, or viacommon control interface 72.

APU controller 70 responds to requests presented on a common controlinterface 72 provided within APU controller 70. Similarly, APUcontroller 70 responds to directly connected components of APU 50, suchas fault sensors 96, as if they were requests. As used herein, bothsources of input are considered requests. In response to these requests,APU controller 70 performs various actions including controllingoperation of various components provided within APU controller 70 andreading and/or writing information to an APU controller memory 98.

As shown in FIG. 3, APU controller 70 is electrically connected tocommon control interface 72, which may be electrically connected to alocomotive control system via a control connection cable 100 coupled tocommon control interface 72. In some embodiments, multiple commoncontrol interfaces 72 may be provided to facilitate connection of APUcontroller 70 to multiple locomotive controllers and to provideelectrical isolation between the locomotives and APU 50. Each controlconnection cable 100 may utilize connectors to facilitate the rapidconnection/disconnection of APU 50 with a locomotive.

Preferably, control connection cable 100 is configured to interface witha CANbus connection or an established locomotive control systeminterface according to various embodiments. The nature and type of theinterface may vary, as may the number of control interfaces interfacedwith, without departing from the design.

In an alternative embodiment, common control interface 72 is an RFinterface that permits a locomotive controller to control APU 50 withoutthe use of a control connection cable 100. The RF interface permits APUcontroller 70 to interact with RF-enabled locomotive controllers andwith RF-enabled trackside equipment. The RF-interface permits requestsand notifications, and in particular, APU controller memory 98 to beinterrogated and optionally written to using RF-based technologies suchas RFID. This enables trackside equipment to interrogate APU controllermemory 98, and to write updated information into memory 98 (such as newmeter limits) absent a physical connection to APU controller 70.

In some embodiments, the control connection cable 100 is a multi-wirecable that carries engine control signals (e.g., RPM, generatorexcitement voltages, return sensor readings) between APU 50 and thelocomotive controller. Multi-wire cable carrying signals over longdistances in high electro-magnetic interference environments isparticularly susceptible to signal degradation due to cable length,shorting, or improperly seated connectors, and induced electrical noise.As described above, APU controller 70 may comprise circuitry to detectand compensate for these types of errors induced by control connectioncable 100. Given the low current and voltages present for engine controlsignals and direct sensor readings, these issues can often be severeenough to cause the APU 50 to cease functioning and must be accountedfor when passing engine control signals between locomotive car bodies.Alternatively, the compensation mechanisms may be embodied in controlconnection cable 100.

APU controller 70 and common control interface 72 may provide additionalcontrol adaption circuitry (not shown) that adapts control signalsreceived by APU 50 to account for interference and operating conditions.This adaption circuitry is collectively called control adaptors herein.

APU controller 70, common control interface 72, or control adaptors mayadapt its configuration to provide line conditioning based upon knownissues with the control cable between APU 50 and the locomotivecontroller. In one embodiment, APU controller 70 determines a length oftravel of the between the locomotive controller and APU controller 70based on a length of cable stored in memory module 98 (FIG. 7).Alternatively, APU controller 70 may be configured to determine a lengthof travel of the power command by transmitting a signal through controlconnection cables 100 similar to the technique used by a time domainreflectometer. In one embodiment, APU controller 70 includes an optionalsignal booster 102 (shown in phantom in FIG. 3), that boosts the signalreceived by APU 50 to account for the signal degradation.

In other embodiments, APU controller 70, common control interface 72, orcontrol cable adaptors translate the engine control signals and returnsensor readings between locomotive controller values and thecommunications techniques used by the common control interface. Thistype of control adaptor permits an APU 50 to be directly controlled by alocomotive controller that is unaware that APU 50 is not anengine-generator for which it was previously configured, whilstpermitting the use of common control interface 72 for othercommunications with locomotives and fuel assemblies.

According to various embodiments, APU controller 70 is a PLC ormicro-controller, along with associated memories 98 and volitileregisters (not shown), that provides control electronics for theelectronic monitoring, control and reporting of APU operation. APUcontroller 70 may receive operating power any number of sources,including common control interface 72, from its internally generatedpower, or other power source (not shown) such as, for example, aninternal battery or an external power source. This combination ofconnections permits APU controller 70 to identify, select, and managethe state of the fuel being received, and configure engine 78 to (e.g.,optimally) burn the currently provided fuel(s).

According to various embodiments, APU controller memory module 98 maycomprise non-volatile memories, either read-only or read-write, such asROM or EEPROM, that are used to store information about the identity,capabilities, contents, and/or historical operations of APU 50, asdescribed below.

In one embodiment, APU controller memory module 98 includes a first APUmemory 104 that includes identifying information that may be used touniquely identify APU 50, such identifying information may include apower curve specific to APU 50, and may further include informationdescribing generating and/or power capacity of APU 50, acceptable fueltypes for use with APU 50, shutdown delay interval, and the like.

APU controller memory module 98 may also include a second APU memory 106that stores information about the cost of power provided by APU 50, andany limits on the use of power from APU 50. These limits may include anamount of contracted power (limit and/or remaining).

APU controller memory module 98 may further include a third APU memory108 that stores information related to the operation of APU 50,including historical sensor readings (e.g., fuel type, temperature andpressure over time), power produced and delivered, use history, andsimilar history of operating information, as well as inspection history.

APU controller 70 may operate using meter 92 and its memories 98, 104,106, 108 to determine if there are deliverable power thresholds, andenable/disable power delivery using controllable switch 88 if the limitshave been reached. In some embodiments, such as where the railroad ownsand operates APU 50, for example, the use of meter 92 and the trackingof limits in the amount of power delivered by APU 50 may be curtailed.

Referring to FIGS. 2 and 3 together, in operation, APU 50 transmits aninquiry to fuel assembly manager 62 of fuel assembly 52 to determineidentifying information of fuel assembly 52. As examples, APU 50 mayinquire regarding a type of fuel within pressure tank 60, determinerequested delivery characteristics of fuel, including delivery pressureand temperature, based upon the type of fuel and/or fuel energycontent), and transmit a fuel delivery request to fuel assembly manager62 based on identified type of fuel. In response to the transmittedrequest, fuel assembly manager 62 regulates delivery temperature and/orpressure of the fuel.

APU controller 70 may receive requests from one or more locomotivecontrol systems and provide the respective responses to these locomotivecontrol systems, according to various embodiments. APU controller 70 mayalso provide periodic or asynchronous notifications to one or morelocomotive control systems as described below. These instructions arereceived over at least one of control interfaces 72. APU controller 70manages these requests in order to respond separately to requests fromdifferent interfaces.

Example of requests and responses include:

Report identifying information about APU 50, its engines 78, and/orattached fuel assemblies 52. APU controller 70 responds to the requestby providing identifying information about one or more aspects of APU 50(e.g., its identification type, a serial number), its engines 78 (e.g.,engine type, rated horsepower, serial number), and the attached fuelassemblies 52 (e.g., fuel assembly ID, date of last pressure test). Oneskilled in the art will recognize that the number and types ofidentifying information to be provided may extend beyond the examplesset forth above depending on upon specific implementation aspects ofengines 78 and fuel assemblies 52.

Report presence of APU 50. APU controller 70 responds to a requestregarding the presence of APU 50 by providing APU 50 the readiness toprovide power.

Report on the status of APU 50. APU controller 70 reads one or morememories and/or registers of APU controller 70 and/or attached fuelassemblies 52, or meters and/or sensors of APU 50 and/or fuel assemblies52, and reports the requested values of the memories, registers, meters,and/or sensors to the requesting locomotive controller.

Read and/or set particular memories of APU controller 70 and/or attachedfuel assemblies 52. APU controller 70 operates on the specified memoriesand/or registers, causing their values to be read, set (or reset) asspecified in the request. Setting a memory may involve clearing, settingthe memory to a particular value, or incrementing or decrementing thevalue stored in the memory.

Report operational parameters request. APU controller 70 reads theoperational parameters requested from APU controller 70 registers and/ormemories and returns them in the response to the request.

Report control parameters request. APU controller 70 reads the controlparameters requested from APU controller 70 registers and/or memoriesand returns them in the response to the request.

Start request. APU controller 70 operates based on the configuration ofAPU 50, and takes the following steps to implement this request: A)Selects a fuel source and turns on the related valve 68; B) Configuresgenerator 84 to produce no power; C) Configures power interfaces 94 totransmit no power to the locomotives; and D) Starts APU engine 78 andsets it to idle.

Emergency Stop request. This request is made by the locomotivecontroller when there is an emergency condition that requires theimmediate shutdown of APU 50. APU controller 70 operates on theconfiguration of APU 50, and takes the following steps to implement thisrequest: A) If equipped with the optional resistive load, shunt theresistive load across the outputs of generator 84, or if APU 50 isconfigured with a quick-unload generator, configure generator 84 toimmediately adjust the output power; B) Send a notification to allconnected locomotive controllers that APU 50 will discontinue providingpower; C) Disable power interfaces 94 by logically commanding eachswitch 192 to disconnect APU 50 from a connected locomotive; D) Turn offthe controllable valve 68 to disconnect fuel assemblies 52; E) ConfigureAPU engine/generator 78, 84 to produce no power by adjusting the engineand generator configurations; F) Turn off APU engine 78 using thecontrol interface 72 to engine 78; and G) Send notification to allconnected locomotive controllers that APU 50 is offline.

Stop request. APU controller 70 operates based on the configuration ofAPU 50, and takes the following steps to implement this request: A) Senda notification to all connected locomotive controllers that APU 50 willdiscontinue providing power; B) Set a timer until power down using theshutdown delay interval configured in either the request or APUcontroller memory 98; C) Monitor the control interface 72 for poweradjustment requests to remove APU 50 from the power requirements of theconnected locomotives, servicing those requests as they arrive; D) Uponexpiration of the timer, or when no power is requested from APU 50,configure APU engine/generator 78, 84 to produce no power by adjustingthe engine and generator configurations; E) Disable the power interfaces94 by logically commanding each switch 192 to disconnect APU 50 from aconnected locomotive; F) Turn off APU engine 78 using the controlinterface 72 to engine 78; G) Turn off controllable valve 120 todisconnect fuel assemblies 52; and H) Send notification to all connectedlocomotive controllers that APU 50 is offline.

Power request. Power request to provide a specific amount power to alocomotive traction bus, as described in more detail with respect toFIG. 4. The request may further comprise an urgency indicator, whichindicates to APU controller 70 the urgency of the request. Urgentrequests cause APU controller 70 to reorder the operating steps toremove power flowing from APU 50 first, and then adjust the internaloperations of APU 50 for efficient operations. APU controller 70configures controllable switch 88 and electric regulator 90 to deliverthe requested amount of power to the power output. In someimplementations, controllable switch 88 and electric regulator 90 may bethe same device. Power delivered to the power output is may be meteredusing meter 92, which is read by APU controller 70. APU controller 70may report these readings to common control interface 72, and/or storethem in APU controller memory 98 for later use.

APU controller 70 operates on the APU configuration, and takes thefollowing steps to implement this request: A) If the request is urgentand the power request is for a reduction in power provided (including areduction to 0), configure power interface 94 attached to the requestinglocomotive to provide the amount of requested power, or if the amount ofpower requested reduces the overall amount of power delivered by morethan a threshold stored in an APU controller memory 98, treat thereduction as an unloading request (see below); B) Total the requestedpower from all current locomotive power requests; C) Determine theamount of power that APU 50 can generate (in some cases, this value isstored in APU controller memory 98, in other cases, the amount of powerAPU 50 can generate is a function of fuel currently selected, altitude,temperature, and other operating parameters and is calculated by APUcontroller 70); D) Determine if all of the request power can beprovided, and if not, reject the request by sending a response back tothe requesting locomotive controller; E) Configure engine 78 andgenerator 84 to produce the desired amount of power; F) Configure powerinterfaces 94 to provide the amount of requested power to each attachedlocomotive; and G) Send response to the locomotive controllersindicating the new power level being provided.

Adjust power/unloading: The locomotive controller requests that APU 50reduce the power it provides to the locomotive, typically for a shortperiod of time. These types of requests are made by the locomotivecontroller when it encounters wheel slip or adhesion issues, andtypically specify an amount of temporary power reduction. Unloadingrequests are often time critical and require priority handling by APUcontroller 70. In some cases, the request will also include anindication requesting “rapid” removal of power. APU controller 70operates on the APU configuration, and takes the following steps toimplement this request: A) If the reduction in power requested is morethan a first threshold configured in APU controller memory 98 and rapidremoval of power is requested, configure generator 84 to quicklydiscontinue power generation by generator 84 by activating features ofgenerator 84 designed quickly reduce the amount of power produced bygenerator 84; B) Configure power interface 94 connected to therequesting locomotive to adjust the amount of power provided to thelocomotive by changing the configuration of power regulator 90; E)Configure APU engine/generator 78, 84 to produce the requested amount ofpower by adjusting the engine and generator configurations; and G) Sendresponse to the locomotive controllers indicating the new power levelbeing provided.

As would be understood by one skilled in the art, other requests andresponses may be added to APU controller 70 without deviating from thescope of this invention.

APU controller 70 also services fault indications, either from faultsensors directly connected to APU controller 70 or from notificationsreceived thru common control interface 72. After receiving a faultindication, APU controller 70 determines the nature of the fault and itsexpected response. The list of faults and expected responses ispreferably stored in a configuration memory of APU controller 70. Anexemplary list of faults and their responses is given below:

Control interface lost to locomotive controller: APU controller 70implements transient and extended loss of the control connection betweenAPU 50 and the locomotive controller. When a loss or corruption ofsignal is detected by APU controller 70, APU controller 70 checks itsfault sensors to determine if one or more faults have been detected inconnections between APU 50 and locomotive. If not, APU controller 70checks for resumption of the signal within a time limit specified by aconfiguration threshold defined in APU controller memory 98. APUcontroller 70 may optionally transmit one or more messages to thelocomotive controller informing it of the loss of signal. If the signalis not restored within the specified time limit, APU controller 70implements an immediate cessation of power provision at power interface94 corresponding to the locomotive controller for which control signalswere lost, and then implements a power command to stop generating powerfor that locomotive. An exemplary embodiment describing how power isremoved from power interface 94, see “Power interface fault” handlingbelow. APU controller 70 may also transmit to the locomotive controlleroperational or status information indicating its change in powergeneration.

Power interface fault: APU controller 70 implements both an immediatedisconnect of APU 50 from the locomotive connected to power interface94, and also implements a power command to stop generating power forthat locomotive corresponding to power interface 94 and by changing thesettings on electrical manager 86 components in order to quickly removecurrent from power interface 94. For example, APU controller 70 maylogically control switch 88 to disconnect power between APU 50 andlocomotive. Alternatively, APU controller 70 may control the regulator90 to provide no power to power interface 94. The control instructionssent to the electrical manager components will vary depending upon thetypes of components and their response time and ability to operate whencarrying a full current load. For example, APU controller 70 may adjustregulator 90 to reduce the current flow, and then disconnect usingswitch 88, or may simply open switch 88 depending upon the amount ofcurrent flowing at the time. Additionally, APU controller 70 mayconfigure generator 84 to quickly discontinue producing power byactivating the rapid power removal features of generator 84. The preciseorder and nature of component controlling by APU controller 70 may beadjusted without deviating from the scope of the invention, and isdictated by the amount of power currently being provided, the number oflocomotives for which power is being provided, and the limitations ofthe power switching and regulation hardware used. APU controller 70 mayalso transmit to the locomotive controller operational or statusinformation indicating its change in power generation.

Equipment fault: APU controller 70 receives this fault if a piece ofequipment in APU 50 malfunctions or ceases to operate. These types offaults may include cooling fan failure, fuel interface failures, powerinterface failures, and the like. APU controller 70 determines, basedupon a table of equipment and fault type, one or more appropriateresponses from the following: A) Shutting down APU 50; B) Removing thefaulting equipment from use (and removing that part of the APU'sfunctionality); C) Notifying one or more locomotive controllers of thefault (and any new configuration or control values such as the amount ofpower available); D) Logging the fault in APU controller memory 98; E)Recalculating fuel and power efficiency graphs and power availablevalues and updating the values stored in APU controller memory 98; F)Reducing the amount of power provided to one or more power interfaces;and G) Taking no action, as examples. Each of these actions maytranslate into one or more APU requests that are processed by APUcontroller 70.

In an example, upon receiving a disconnect signal, APU controller 70 isconfigured to initiate a shutdown protocol for auxiliaryengine-generator set 82. The shutdown protocol may logically disconnectall power interfaces (as described above), stopping power generation byinstructing the generator to stop producing power, include shuntingauxiliary engine-generator set 82 within a very short time period afterdetecting the disconnection, such as, for example, approximately 10milliseconds, and turning off auxiliary engine-generator set 82.

In some cases, the faults recorded by APU controller 70 are operationalin nature, such as control panel being opened or a connect/disconnectoccurring on an interface that is not currently in use. In these cases,APU controller 70 actions may include: logging the fault, taking noaction, sending a notification via a common control interface 72.

APU controller 70 also handles other operational aspects of APU 50. Someof these aspects and the APU controller's 70 handling of them aredescribed below.

When operating with removable fuel assemblies 52, APU 50 may receivenotifications of fuel assembly being added or removed from APU 50. Whena new fuel assembly is added to an APU configuration, APU controller 70communicates with fuel assembly using control interface 72 to determinethe fuel assembly information, including ID, type of fuel, amount offuel, and other parameters. APU controller 70 then stores thatinformation in APU controller memory 98. APU controller 70 thenrecomputes operating parameters based upon the fuel information andupdates its operational graphs to represent operation using the fuel infuel assembly 52.

APU controller 72 performs power cost calculations when factors relatedto the cost of providing power changes. In an embodiment, the power costcalculation is a calculation based upon the cost of fuel and aconversion factor indicative of the power source's efficiency ofconverting a unit of fuel into power (e.g., kilowatts per gallon). Thecalculations can also utilize the energy content of fuel provided. Insome embodiments, the calculations produce a scalar value. In others,they produce an n-dimensional based upon one or more engine performancemetrics (e.g., amount of power produced, engine RPM, generatorexcitement voltages, one or more metrics related to the fuel being used(price of fuel, energy content of fuel), and one or more metrics relatedto operating conditions (e.g., temperature, air pressure). The resultsof these calculations are stored in memory module 98 of APU 50 forfurther use.

APU 50 may need to switch a fuel source/fuel assemblies as a first fuelassembly 52 becomes empty. If APU 50 can be shut down, this is a simpleprocess of closing valve 68 to the first fuel assembly 52 and openingthe valve 68 to the second fuel assembly 52. The operation is morecomplex when the switch must occur “on the fly”, and even moreparticularly when the pressure tanks 60 of fuel assemblies 52 holddifferent fuels and differing engine operating parameters are associatedwith using each type of fuels most efficiently. In this case, APUcontroller 70 opens valve 68 corresponding to both pressure tanks 60simultaneously, allowing the fuels to mix in common manifold 238. APUcontroller 70 then adjusts pressure regulator 80 and engine parametersto burn the mix of fuels. After engine 78 has stabilized on the mix offuels, valve 68 on the first tank is closed and pressure regulator 80and engine parameters are again reset to optimally burn the fuel fromthe second tank. A similar procedure can be used to transition betweentanks when a first tank is running out of fuel.

One aspect of APU 50 with multiple interchangeable fuel assemblies 52 isthat fuel assemblies 52 can be changed “on the fly” while APU 50 isstill operating. This is accomplished by the following process: A) APUcontroller 70 transitions fuel use to fuel assembly 52 that is not beingchanged and closes valve 68 on the fuel assembly to be changed; B)Control cabling and fuel hoses are disconnected (APU controller 70recognizes the disconnect, but takes no action because the tank isalready logically disconnected from APU 50); C) Fuel assembly 52 isunattached from APU 50, and then physically removed from APU 50 a newfuel assembly is attached to APU 50 in its place, and the fuel andcontrol lines attached; D) APU controller 70 recognizes a new fuelassembly is attached, and performs the “new fuel assembly” processdescribed above.

Changes in operating conditions, fuel assemblies, equipment status, andrelated items occasionally cause APU controller 70 to recalculate itscontrol parameters. For example, if different settings are needed forengine 78 to attain a specific power level, APU controller 70 is awareof this from its monitoring of engine performance vs. power output. Ifthe difference is greater than a threshold set in APU controller memory98, APU controller 70 calculates the new operational parameters andrecalculates its performance graphs. After storing these new parametersand graphs, it notifies any attached locomotive controllers of the newparameters and graphs.

Similarly, APU controller 70 changes such as the change in controlparameters, available, or currently used fuel may results in differingtotal costs of power produced by APU 50. In these circumstances, APU 50recalculates its power cost and power cost graphs, and stores them inAPU controller memory 98, and then notifies any locomotive controllersconnected to APU 50 of the changes in power cost.

The above description provides an autonomous APU that can provideauxiliary power to one or more locomotives upon receiving commands fromeach locomotive's locomotive controller. An APU that is able to takecertain actions autonomously offloads the work of the locomotivecontroller, permits an APU to provide power to multiple locomotivesindependently, handles certain fault conditions that the locomotivecontroller cannot handle, and generally improves safety and operationalcharacteristics of providing power to locomotive power buses.

The response time to certain faults when providing power between railcars a key factor to operating safety. For example, a severed powercable energized with 1Mw of power is hazardous to rail equipment,locomotive operators, and nearby people. Similarly, automated connectionand valve management of fuel input lines when switching fuel sources isalso important. Lastly, recognizing APU-specific faults and operatingconditions in sufficient time to react and mitigate any operationalissues that arise lets the APU operate within the locomotive controllerhaving detailed knowledge of internal APU workings. The APU controllertypically needs to respond to change in operating conditions veryquickly (e.g., within 10 msec, 100 msec, 1 sec, or 10 sec, dependingupon the type of change). For example, ground faults and disconnectionfaults (when the power interface is powered) should be responded toquickly to de-energize the power bus. Similarly, fuel system faultsshould be responded to quickly to prevent fuel spills. Other operationalissues, such as fuel amounts crossing a lower threshold, chassistemperature or alarms, for example, can be handled more slowly. Stillother operations, particularly those that require communicationsinteractions with fuel assemblies or lengthy calculations, may completein 10 or more seconds.

One important aspect of APU controller handling is response time tolocomotive controller requests. Locomotive controllers operate in veryshort duration control loops, and response time of APUs to locomotivecontroller requests is important to the successful operation of alocomotive control with an autonomous APU. Accordingly, the APUcontroller must provide response times to requests received fromlocomotive controllers within a configuration defined amount of time(varies depending upon the locomotive controller) or be considerednon-responsive. A non-responsive APU controller would be considered afault condition by the locomotive controller and be handled accordingly.Some locomotive controller requests may contain an indication that therequest should be handled quickly, such as power removal requests beinggenerated in conjunction with wheel slip or fault events.

Referring now to FIG. 4, a locomotive consist or locomotive assembly 110is illustrated that includes a genset locomotive 112 coupled toauxiliary power unit assembly 48 described with respect to FIGS. 2 and3. As shown, genset locomotive 112 includes a primary locomotivecontroller 114 that manages multiple locomotive engine-generator sets116 that operate in response to received commands from primarylocomotive controller 114. While genset locomotive 112 is illustrated asincluding two locomotive engine-generator sets 116, genset locomotive112 may include additional locomotive engine-generator sets according tovarious embodiments. Further, according to an alternative embodiment,locomotive assembly 110 may be configured with a locomotive having asingle engine-generator set.

Each locomotive engine-generator set 116 includes a respective engine118, generator 120, and sensor system 122. Generators 120 produceelectricity for delivery to a locomotive traction bus 124 and anauxiliary power bus 126. Generators 120 are configured to convert themechanical energy provided by engines 118 into a form acceptable to oneor more traction motors 128 (DC or AC type) configured to drive theplurality of axles coupled to the driving wheels 130 of locomotive 112,and to provide DC or AC power to the respective auxiliary power bus 126.

Locomotive 112 also includes an engine start and stop control 132 whichinterfaces with primary locomotive controller 114 and is linked tolocomotive engine-generator sets 116 to initiate their operation and toterminate their operation. Engine start and stop control 132independently controls each locomotive engine-generator set 116. Sensors116 of each locomotive engine-generator set 116 provide information toprimary locomotive controller 114 regarding the status and/or operationof each locomotive engine-generator set 116 (e.g., various parameters ofthe engines 118 such as rpms, operating power output, temperature andother engine operating parameters).

In some embodiments, one or more locomotive engine-generator sets 116are operated in response to a throttle position input sensor 134 (or anrpm sensor) which indicates the position of the throttle as controlledby the operator on an operator interface 136. Operator interface 136 mayalso include an optional operator engine start input 138 (shown inphantom) where the operator can directly or indirectly instruct primarylocomotive controller 114 (e.g., via a keypad (not shown)) with regardto operation of engines 118 or termination of operation of the engines118.

The correlation between engine RPM (or throttle setting) and the amountof electricity generated is stored within primary locomotive controller114. Power sensors 140 on the locomotive fraction bus 124 and auxiliarypower bus 126 provide information to primary locomotive controller 114on the amount of power actually being provided on the busses 124, 126.Primary locomotive controller 114 manages the amount of power present onthe busses 124, 126 by adjusting the engine RPM and generator excitement(by changing the control voltage) and by measuring the amount of powerpresent on the various busses 124, 126 using the power sensors 140.Primary locomotive controller 114 also calculates and manages locomotivelocation and anticipated power needs.

Genset locomotive 112 is connected to APU 50 of auxiliary power unitassembly 48 by way of a number of power cables 142 and control cables100. The number of control cables 100 is determined based on designspecifications for the amperage and interconnection between locomotive112, APU 50, and fuel assemblies 52. In some embodiments, locomotivecontroller 114 provides APU control instructions on a dedicated APUcontrol interface. In a preferred embodiment, this interface providessignaling that is electromagnetic interference (EMI) resistant (e.g.,CANbus). In other embodiments, control cables 100 may include converters(described above) that convert locomotive controller engine controlvoltages (e.g., RPM, generator excitement) to/from EMI resistantsignaling means. In other embodiments, control cables 100 may includeconverters (not shown) to convert locomotive controller engine controlvoltages (e.g., RPM, generator excitement) to APU controllerinstructions. These converters may be implemented individually or inseries as desired to provide a signaling path between the locomotivecontroller 114 and APU control interface 72. While APU 50 is illustratedin FIG. 4 as being connected to a single genset locomotive 112, oneskilled in the art will recognize that APU 50 may be coupled to multiplelocomotives via respective sets of power and control cables.

According to one embodiment, at least one of APU controller 70 andprimary locomotive controller 114 is configured to detect a fault in thetransmission of power and/or control commands through control cables100. Upon detection of the fault, primary locomotive controller 114 maybe configured take one or more actions in response to the faultcondition. If the fault condition is in the control cable connection 100between the locomotive controller 114 and APU 50, example actions mayinclude: resend one or more the power and/or control commands to APU 50,send a status command to APU 50, read one or more sensors and make adetermination of the seriousness of the fault condition, alert thelocomotive operator thru a display or alerting device (e.g., light,alarm signal). Other actions may be programmed into the locomotivecontroller 114 in response to communications faults between thelocomotive controller and APU 50 as would be understood by those skilledin the art. Alternatively, or in addition thereto, primary locomotivecontroller 114 may be programmed to modify a previously sent powercommand upon detection of the fault, or to set APU 50 to an“unavailable” status and reallocate power requirements allocated to APU50 to other engine/generators. For example, if APU 50 is showing aconnection fault on its command circuit and it is not providing power tothe power bus 124 as indicated by power bus sensors 140, locomotivecontroller 114 may decide that APU 50 is no longer functioning andreallocate the power requirements allocated to APU 50 to a primarylocomotive engine/generator 116, causing it to increase its RPMs andalternator excitement voltages in order to provide the missing power tothe power bus.

In some instances, locomotive controller 114 is expecting a responsefrom APU controller 70 that is not received, or is receiving in anunusable form. In this case, the locomotive controller 114 may take oneor more actions to respond to the missing response. For example, theseactions may include any or all of the following: resend one or more thepower and/or control commands to APU 50; send a status command to APU50; read one or more sensors and make a determination of the seriousnessof the fault condition; alert the locomotive operator using a display oralerting device (e.g., light, alarm signal). Other actions may beprogrammed into locomotive controller 114 in response to communicationsfaults between locomotive controller 114 and APU 70 as would beunderstood by those skilled in the art.

In other instances, locomotive controller 114 may receive notificationsfrom APU controller 70 asynchronously. These notifications may compriseevent or alert notifications, or may simply comprise informationprovided by APU controller 70 that locomotive controller 114 mayconsider in managing locomotive consist 110. The actions taken bylocomotive controller 114 in response to these notifications may includeany or all of the following: do nothing, send a command to APUcontroller 70 requesting additional information about APU controllermemories 98; process the received information as a fault indication oras a connection notification; process the received information as asensor reading related to APU operation; store the received informationin locomotive controller memory 146 for use during power costcalculations; store the received information in locomotive controllermemory 146 for use in subsequent power allocation calculations;recalculate the cost of power provided by APU 50 for use in powerallocation decisions; reallocate power allocation to APU 50; and commandAPU 50 to provide a differing amount of power to locomotive power bus124. Other actions may be programmed into locomotive controller 114 inresponse to notifications received by locomotive controller 114 from APU50 as would be understood by those skilled in the art.

In operation, primary locomotive controller 114 transmits power requestsignals to APU controller 70 via control cables 142. Responsive toreceipt of the power request signals, APU controller 70 selectivelycontrols the auxiliary engine-generator set 82 to produce a desiredamount of power. The power produced by APU auxiliary engine-generatorset 82 is then transmitted to locomotive traction bus 124 via powercables 142.

While auxiliary power unit assembly 48 is illustrated in FIG. 4 as beingdirectly connected to genset locomotive 112, the distance betweenauxiliary power unit assembly 48 and genset locomotive 112 may varygreatly with the addition of additional locomotives and/or additionalauxiliary power unit assemblies to locomotive consist 110. Dependingupon the length of travel of the power command between the primarylocomotive controller 114 and the APU controller 70, a certain amount ofvoltage drop will occur in the power command causing a signaldegradation of the originally transmitted power command. According toone embodiment of the invention, APU controller 70 is configured toidentify an amount of signal degradation in the power command receivedfrom primary locomotive controller 114 and adjust the power command toaccount for the identified signal degradation. APU controller 70 thenuses the adjusted power command to selectively control auxiliaryengine-generator set 82. In one embodiment, APU controller 70 determinesa length of travel of the power command based on a length of cablestored in memory module 98 (FIG. 3). Alternatively, APU controller 70may be configured to determine a length of travel of the power commandby transmitting a signal through control cables 100 similar to thetechnique used by a time domain reflectometer. In one embodiment, APUcontroller 70 includes an optional signal booster 102 (shown in phantomin FIG. 3), that boosts the power command received by auxiliary powerunit 50 to account for the signal degradation.

APU units 50 provide identifying information to primary locomotivecontroller 114 via control interface 72. This identifying informationincludes identifying information from memory module 98 of APU 50 as wellas identifying information from memory module 206 of fuel assemblies 52coupled to APU 50. As described above with respect to FIGS. 3 and 7,indentifying information stored within memory modules 206, 98 mayinclude an equipment configuration of APU 50 and a cost of fuel withinfuel assembly 52 as examples. Based on the identifying informationreceived from APU 50 and a current total power demand of gensetlocomotive 112, primary locomotive controller 114 makes a determinationas to how to allocate power generation between locomotiveengine-generator sets 116 and auxiliary power unit 50. According to oneembodiment, APU 50 is programmed to periodically transmit identifyinginformation to primary locomotive controller 114, such as, for example,(as a notification) at predefined time intervals.

According to one embodiment, primary locomotive controller 114 is alsoin communication with one or more fuel assemblies 52, which providegaseous fuel to one or more of the locomotive engines 78 and/or APU 50.Fuel assemblies 52 also provide sensor information regard fuel state,fuel type, and fuel costs to primary locomotive controller 114.

As shown in FIG. 4, a disconnect sensor 144 is coupled to power cables142, which electrically connect genset locomotive 112 and APU 50.Disconnect sensor 144 is configured to sense a connection status ofauxiliary engine-generator set 82 with locomotive traction bus 124.Should a decoupling occur between genset locomotive 112 and rail car 56and/or a disconnection occur between power cables 142 and locomotivetraction bus 124, disconnect sensor 144 will transmit an alert signal toat least one of APU controller 70 and locomotive controller 114indicating the disconnection.

According to one embodiment, primary locomotive controller 114 is atraditional locomotive controller that has been modified to permit itrecognize and to communicate with APU 50 and fuel assemblies 52. A firstmodification is for primary locomotive controller 114 to recognize thatone or more of its power sources may be intermittently present, havediffering identifying information each time it is connected, may havediffering operating characteristics from time to time, and may providepower at a differing cost that the primary engine/generator(s) 116 onthe locomotive chassis.

Locomotive controller 114 may recognize that something is connected toits control line based upon the presence or absence of voltage, currentor capacitance on the line. Upon recognizing the connection of a newdevice to the locomotive control line (and the connection of the powerand control circuits or cables), locomotive controller 114 undertakesthe following steps to determine information about APU 50: A)Communicate with the device to determine if indicated connection was toan APU, a fuel assembly, or some other device, and if the device is notan APU or fuel assembly, locomotive controller 114 takes an actionconsistent with a fault handling (as described above); B) locomotivecontroller 114 sends a command to the device to determine deviceidentifying information and receives a response, and if a response isnot received, it is handled as described above; C) locomotive controller114 optionally sends additional commands to the device and receivesadditional responses from the device to determine additional informationabout the device, or looks up information about the device, either in alocal memory or from a remote computer, to determine the additionalinformation, D) Locomotive controller 114 stores the informationreceived in memory 146 for subsequent use; and E) Based upon the type ofdevice connected, locomotive controller 114 takes additional actionsselected from the set of actions: perform power cost calculations,perform power allocation, send a power command to APU 50, and select afuel assembly.

Locomotive controller 114 performs power cost calculations as the costof providing power changes. In an embodiment, the power cost calculationis a scalar value provided by an external device, a calculation basedupon the cost of fuel and a conversion factor indicative of the powersource's efficiency of converting a unit of fuel into power (e.g.,kilowatts per gallon). The calculations can also utilize the energycontent of fuel provided. In some embodiments, the calculations producea scalar value. In others, the calculations produce an n-dimensionalbased upon one or more engine performance metrics (e.g., amount of powerproduced, engine RPM, generator excitement voltages, one or more metricsrelated to the fuel being used (price of fuel, energy content of fuel),and one or more metrics related to operating conditions (e.g.,temperature, air pressure). The results of these calculations are storedin locomotive controller memory 146 for further use.

Locomotive controller 114 sends a power command to APU controller 70instructing it to provide a specific amount of power to the power bus.Optionally, this power command may include an indication that the powercommand should be performed quickly, such as when locomotive controller114 is processing wheel slip or faults. The power command send to APUcontroller 70 typically differs from normal engine control voltages inthat it specifies an amount of power (current and voltage) to providebecause locomotive controller 114 is generally unaware of the powersource settings associated with providing a desired amount of power.Because locomotive controller 114 is unaware of these settings permits,locomotive controller 114 can interoperate with APUs 50 using differingpower sources. This provides a significant operational advantage.

After locomotive controller 114 sends a power command to APU controller70, APU controller 70 responds to locomotive controller 114 in severalways. First, APU controller 70 responds to the power command with aresponse on the control cable connection 100 to the requestinglocomotive controller 114. If locomotive controller 114 does not receivethe response within a configuration determined timeframe, locomotivecontroller 114 takes corrective action as described above for missedresponse. Secondly, locomotive controller 114 monitors sensors 140 onpower bus 124 to determine if APU 50 as provided the requested power. Ifthe power requested does not appear on power bus 124 within aconfiguration determined, or dynamically determined timeframe,locomotive controller 114 handles this failure to respond as a fault (asdescribed above).

One aspect of locomotive controller 114 is to manage locomotive consist110 with respect to overall emissions produced. APUs 50 may provide tolocomotive controller 114 information (graphs or scalar metrics) thatrepresent the emissions produced or with respect to emissions producedby each engine. APU 50 under specific operating conditions. In order toobtain emissions levels which adhere within certain limits or whichbetter match certain target objectives, locomotive controller 114 maydetermine that APU 50 should operate using a certain balance of one fuelin preference to another (e.g., natural gas as opposed to syngas), or touse a certain mix of the two fuels over a particular time scale. Forinstance, a locomotive may not be able to achieve desired management ofboth NOx and particulate matter emissions over a certain distance ortime by running natural gas 100% of the time. Locomotive controller 114makes this determination based upon higher level calculations based inpart upon the emissions profile of the power sources available tolocomotive controller 114, their emissions profile under particular loadconditions, fuels available, and the location of locomotive 112 and itsprojected load conditions. Locomotive controller 114, when making thesecalculations, adds the steps of sending a request to one more of the APU50, fuel assemblies 52 to determine the fuel types and emissionsprofiles for power requests to APU 50. Locomotive controller 114receives the requested information, stores it in memory 146, and thencalculates the emissions profiles. Once the emissions profiles arecalculated, locomotive controller 114 makes a determination regardingfuels to use and power allocations, and instructs APU 50 and/or fuelassemblies 52 appropriately.

The auxiliary power enabled locomotive controller 114, being a gensetstyle locomotive controller, is able to make power allocations betweenpower sources. The difference is that the auxiliary power enabledlocomotive controller 114 is able to determine if an APU 50 isconnected, and if so, use APU 50 as one of the available power sources.

Primary locomotive controller 114 is coupled to a memory module 146within which is stored its current cost of producing power using thestandard power. The current costs of producing power may be a uniquenumber, or may be a sequence of numbers stored a table based upon engineRPM. In one embodiment, memory module 146 also stores a price of fuelfor locomotive engines 78. This price can be manually or electronicallyupdated on a periodic basis. Primary locomotive controller 114, usingthis table, and the known engine RPMS, can compute the cost of providinga unit of power to the locomotive's traction and/or auxiliary powerbusses 124, 126. This cost is called the internal generation cost.

Knowing the current cost of power, primary locomotive controller 114 maythen seek lower cost power from APU 50 when APU 50 is able to providepower for the locomotive busses 124, 126 at costs below the internalgeneration cost. Primary locomotive controller 114 reads the currentpower cost from APU controller 70, and compares the internal generationcost to the price provided by APU controller 70, and selects enginethrottle and APU power settings to obtain power from at least one of thelowest cost source and a combination of sources whose costs aggregate tothe lowest total cost. In some cases, this means primary locomotivecontroller 114 will power down the onboard engines 78 and use only powerproduced by APU 50. In other cases, primary locomotive controller 114will use power generated by both APU 50 and onboard engines 78. In stillother cases, primary locomotive controller 114 will idle APU 50 and useonly onboard power produced by auxiliary engine-generator sets 82.

In one embodiment, the power command transmitted by primary locomotivecontroller 114 will specify an amount of power required and APU 50 willself-configure to provide that amount of power to the locomotive. Inthis way, APU 50 can provide power to multiple locomotives, and run at ahigher level of power production sufficient to provide power to twolocomotives. Power regulator(s) 90 in APU 50 may be used to allocatepower between the locomotives in this case. In other embodiments, thepower command transmitted by primary locomotive controller 114 mayspecify a desired operating point on a performance graph of APU 50 or adesired power level of the output power of APU 50.

In an optimization to this algorithm, railroads may purchase bulk powerfrom power providers using APU 50 as described above. Their powerpurchases may be reporting by the meter 92 in APU 50. Primary locomotivecontroller 114 may interrogate the meter 92 and determine the amount ofpower remaining in the current bulk purchase, and make its powerallocation decisions based at least in part upon the amount of powerpreviously purchased. This is especially advantageous when the bulkpurchases are “use or lose”, and it is advantageous to the locomotiveoperator to use all of their previously purchased power. Depending uponthe embodiment, the optimization algorithm can also include the aspectthat with APU 50 operating, the overall power available to the tractionbus 124 can be higher that with the locomotive(s) alone, and there maybe portions of the route where the higher power has value to therailroad and therefore it is beneficial for the system to reservesufficient fuel for those portions of the route. As such, the algorithmis looking at several time periods to optimize the value of APUoperation, not simply as the minimum cost of power now.

In implementing these operations, the locomotive controller 114 includesseveral steps in its master control routine. The master control routineis executed periodical by locomotive controller 114. The master controlroutine monitors and reacts to operational conditions such as wheelslip, power requirements and availability, and performs powerallocations. In the example set forth below the detection of theoperational condition of wheel slip is described in detail. However, oneskilled in the art will understood that other operational conditionsprocessed by locomotive controller 114 during this master control loopthat initiate adjustment in power allocated or provided by locomotiveconsist 110 follow similar operational patterns and may be implementedwithout deviating from the scope of the invention.

When the locomotive controller control loop starts, it checks for faultsand handles them as described elsewhere. Locomotive controller 114 thenchecks for wheel slip, and upon detecting wheel slip is occurring, itimmediately makes an assessment of the severity of the wheel slip. Ifthe wheel slip is severe, locomotive controller 114 instructs theprimary power sources and the auxiliary power sources currentlyproviding power to locomotive 112 to immediately reduce the amount ofpower provided to locomotive 112 by an amount proportional to the amountof slip. The power reduction may be made across all power sources, ormay be selectively made against one or more power sources withoutdeviating from the scope of the invention. Locomotive controller 114directly configures its primary engine-generators 116 to effect thispower reduction, and sends a power adjustment or a power control messageto a connected auxiliary power source (e.g., APU 50). In both cases, themessage is marked for fast implementation by the auxiliary power source,causing rapid removal of power in accordance to the command. Theselection of a power adjustment or power control message is made bylocomotive controller 114 on the basis of the amount of wheel slipdetected; mild to moderate wheel slip may indicate a short term poweradjustment is appropriate, and more severe wheel slippage may indicatethat a change in power requested is needed. If wheel slip was detected,locomotive controller 114 restarts the control cycle to determine iffaults or operational conditions such as wheel slip are occurring. Onceoperational conditions are processed, locomotive controller 114 checksfor messages from auxiliary power sources 50 or fuel assemblies 52 thathave not been processed. These messages are processed, and storedinformation (e.g., ID information, operational information, etc.) aboutthe power sources and/or fuel assemblies are updated as required. Thesemessages may indicate a change in a removably connected power source 50and/or fuel assembly 52, fuel state or type, the amount of powerprovided by an auxiliary power source, a cost of power provided, anupdated graph, or other change that locomotive controller 114 takes intoaccount when optimizing the performance of locomotive consist 110.

If power, fuel, or cost information is updated, locomotive controller114 then conducts a series of interactions with the power sources andfuel assemblies to update its stored information to current values.Locomotive controller 114 then recalculates any information it hasstored based upon the updated stored values.

After completing the update of the stored information, locomotivecontroller 114 determines information required to support the powerallocation process. This information includes the current amount ofpower required by the locomotive (based upon throttle notch settings,auxiliary loads, traction motor requirements, etc.), and determines thecurrent amount of power available by totaling the amount of power eachpower source may provide. It further determines the power cost for eachpower source, either as a scalar metric or as an efficiency graph thatdescribes the power costs relative to the amount of power provided, oras a metric or efficiency graph based upon the fuel type/composition. Insome cases, fuel cost, operational metrics such as temperature or airpressure, and other metrics are used as inputs in determining the powercost. Other parameters such as power sources requested to produce aminimum amount of power are also collected. In an embodiment, thisinformation may include emissions and or maintenance scheduleinformation about each of the power sources.

Locomotive controller 114 then checks to determine if the power providedto locomotive 112 is within a configuration specified tolerance of thepower required to operate the locomotive. If the power required andpower provided are out of tolerance, or one of the power cost parameterschanged, locomotive controller 114 makes a power allocation between thepower sources, dividing the locomotive power requirement betweenavailable power sources, such as, for example, locomotiveengine-generator sets 116 and auxiliary power sources such as APU 50. Inone embodiment, the power allocation is performed in a way to minimizethe total cost of power utilized by the locomotive, using the power costand minimum/maximum amounts of power produced for each power source asinput. In some embodiments, the power cost is a graph that representsthe varying power cost based upon the amount of power provided.Locomotive controller 114 finds the minimum total cost based upon theamount of power requested, and sets the primary power sources (e.g.,sets generator excitement and RPMs) and sends requests to auxiliarypower sources to provide the desired amount of power.

Power allocation algorithms may be very complex, and may include currentlocation, anticipated power requirements, and other factors in theallocation algorithm. In some embodiments, the power allocation may besimplified to use fuel costs as the allocation factor. For example, whenthe difference between diesel and natural gas fuel prices exceed acertain level, the lower priced fuel is always less expensive tooperate. Similarly, if specific fuels are available, it may moreefficient to operate with those fuels. The results of the powerallocation process are stored in locomotive controller memory 146 forsubsequent use.

Locomotive controller 114, having configured locomotive consist 110 tooperate with a specific source and amounts of power then monitors thepower provided by each power source to determine if the amount of powerbeing provided is in accordance with the settings, and makes adjustmentsto the power source configurations as needed to keep the amount of powerprovided to the locomotive in line with the power requirements. Thecontrol loop then repeats on a periodic interval.

In applications where fuel assemblies 52 have direct control and fuelconnections 148, 150 with locomotive 112, valves 120 of fuel handingsystem 210 (FIG. 6) fluidly connect pressure tank 60 to engines 78.Primary locomotive controller 114 may interrogate each fuel assembly 52,determine the type of fuel, its cost, and its energy density, anddetermine which of the available fuels it should use in the currentsituation based on the information received from fuel assemblies 52.After selecting the fuel to use, primary locomotive controller 114 canconfigure the engine operating parameters (idle, timing, etc.) soengines 78 process the selected fuel most efficiently. For example, itmay be cost effective to use syngas or process gas while engines 78 areidling, and to use LPG when the engines 78 are running at maximum RPM.Similarly, primary locomotive controller 114 can use fuel cost and/orfuel energy density as inputs in determining which fuel should be usedin the current situation.

Referring now to FIG. 6, a fuel assembly 52 is illustrated in accordancewith an embodiment of the invention. Fuel assembly 52 includes a frame152 constructed from multiple top side support members 154 and bottomside support members 156 interconnected by vertical support members 158and cross support members 160. Top side support members 154, bottom sidesupport members 156, vertical support members 158, and cross supportmembers 160 are constructed of any number of suitable support materials,such as, for example, structural steel. According to one embodiment, anumber of tie-downs or fastening structures 162 are coupled to frame 152to removably secure interchangeable gaseous fuel assembly 52 to anexternal support structure (not shown), such as, for example, alocomotive body or frame, a power unit, a rail car body, or anotherinterchangeable gaseous fuel assembly. In one embodiment, fasteningstructures 162 are corner fittings or corner castings similar to thosetypically used in intermodal containers. Such corner fittings have lugreceiving holes on the faces thereof for purposes of receiving liftinglugs. In some embodiments, fastening structures 162 are provided atalternative locations along the bottom side support members 156 of frame152 at locations calculated to permit fuel assembly 52 to be liftedsafely using standard overhead container lifting technologies. Theselugs may be on rail yard-based lift equipment, such as overhead liftgantries, thus allowing for standardized equipment to be used to liftthe interchangeable gaseous fuel assembly 52 for removal and replacementthereof. Similarly, multi-lugged pins may be used to interconnect thecorner fittings 162 of fuel assembly 52 to other intermodal containersby engaging the corner fittings of respective containers to one another.Likewise, pins may be used on railroad locomotives and rail cars chassisto secure fuel assembly 52 in place in order to prevent tipping orupset, as well as for stacking or securing fuel assemblies 52 on roadtrucks or aboard ships. Openings between support members 154-28 provideaccess to the various inlets, outlets, valves, controls, and the like,on or associated with pressure tank 60.

According to another embodiment, a number of slots or openings 164 areformed in the bottom side support members 156 of frame 152. Openings 164are sized to receive lifting fork arm, thereby allowing for lifting forktechnologies to lift light-weight interchangeable gaseous fuelassemblies without the need for yard-based overhead lifting apparatus.

Gaseous fuel assembly 52 may be grounded via its frame 152 and/or theattaching lugs to an underlying auxiliary power unit, railcar body, orlocomotive body in order to dissipate static charges that might igniteleaking gaseous fuel.

A pressure tank 60 is supported within frame 152 and is secured to frame152 via fasteners (not shown) at multiple points. In one embodiment,pressure tank 60 rests on cross support members 160, and is in contactwith at least some of side support members 154 and/or vertical supportmembers 158. Frame 152 is designed such that a frame of a secondinterchangeable fuel assembly (not shown) may be stacked atop frame 152of fuel assembly 52.

Pressure tank 60 is of suitable construction to store a gaseous fuel 166at a temperature and pressure where the fuel 166 remains substantiallygaseous in the stored state. As used herein, “gaseous fuel” means fuelsin liquid or gaseous state (depending upon current temperature andpressure), where the fuel is normally in a gaseous state at standardtemperature and pressure. In many cases, these fuels are hydrocarbonssuch as natural gas, propane, or syngas. Gaseous fuel may also be, forexample, compressed or liquefied hydrogen, producer gas, methane,butane, and the like. Gaseous fuels are measured according to standardsin volumetric units, typically cubic feet or cubic meters, at aspecified temperature and pressure. In these volumetric units, each typeof gaseous fuel stores differing amount of energy, based upon themixture of gases or other components that it contains. The measure ofthis energy is the “energy coefficient” of the fuel. The mixture ofgases can vary based upon the time of year, geographic location the fuelwas obtained from, and other factors. Thus, for example, “natural gas”has a range of typical energy coefficients. Similarly, propane has adiffering range of energy coefficients. In alternative embodiments,pressure tank 60 may store ethanol, diesel fuels, and the like.

According to various embodiments, pressure tank 60 is constructed of oneof a pure metal, a metal composite material, and a composite materialsuch as, for example, steel, aluminum, or carbon fiber. Pressure tank 60may be single walled or double walled and may be insulated, according tovarious embodiments. In an exemplary embodiment, pressure tank 60 isdesigned for nominal operation at 3600 psi, in accordance with industrystandards for gas storage and transportation vessels for compressednatural gas.

Pressure tank 60 may be fitted with one or more relief valves 168, fillvalves 170, a vapor return inlet 172, and an outlet valve 174. Inparticular embodiments, ports (not shown) are added to pressure tank 60in order to accommodate a sensor assembly 176 for measuring attributesof the fuel 166 within pressure tank 60. Sensor assembly 176 includes anumber of probes and/or sensors electrically connected to a fuelassembly manager 62, as described in more detail with respect to FIG. 7.As used herein, the term “sensor” is used to refer to a device capableof producing outputs that can be correlated with one or more physicalproperties of at least a portion of its environment. Examples include,but are not limited to, temperature sensors, pressure sensors, currentsensors, voltage sensors, and fuel flow rate sensors.

According to one embodiment, a cover 178 may be secured to the externalsurfaces of frame 152 in order to protect the pressure tank 60,manifolds, valves, and other components of fuel assembly 52 from weatherand vandalism. Vents or louvers 180 may be formed in a top surface 182of cover 178 to permit air circulation and to avoid the buildup ofexplosive fumes within fuel assembly 52. Advantageously, by situatingvents/louvers 180 at the top surface 182 of fuel assembly 52, anygaseous fuel escaping due to a leak harmlessly dissipates away fromlocomotive 112 and/or locomotive consist 110 when fuel assembly 52 ismounted on top of a locomotive or rail car frame. Furthermore, locatingfuel assembly 52 in this way minimizes the likelihood of damage in aderailment or by impact with track debris or yard traffic.

As shown in FIG. 6, first fuel hose 184 is connected to the outlet valve174 to fluidly connect pressure tank 60 to fuel input 186 of a fuelassembly manager 62, which provides for control electronics for theelectronic monitoring and reporting of tank ID, its contents, and thestate of the contents, changing state and pressure of the gaseous fuelto meet common fuel requirements, as well as delivering a gaseous fuelfrom pressure tank 60 to a fuel outlet 188.

Fuel assembly 52 includes a system of electrical, control, and fuelinterconnects 190 that are provided to couple fuel assembly 52 to alocomotive or railcar mounted auxiliary power unit. This system ofinterconnects 190 can be made using industry standard connectors andhoses (for the gaseous fuel) and industry standard power connectors forthe control and electrical interconnects. In one embodiment,interconnects 190 include a second fuel hose 192, a common controlconnector 194, and an optional electrical power connection 196 (shown inphantom). Second fuel hose 192 is fluidly connected to fuel outlet 188of fuel assembly manager 62. Common control connector 194 electricallyconnects fuel assembly manager 62 to one or more power and/or railroadlocomotive control systems. Optional electrical power connection 196(shown in phantom) is electrically connected to a external power source,such as an auxiliary power generator or a locomotive electrical powerbus (not shown) to receive external power for powering components offuel assembly manager 62, as described in more detail below.

FIG. 7 is a schematic diagram of fuel assembly manager 62 in accordancewith an embodiment of the invention. Fuel assembly manager 62 includes aweather and vandal resistant housing 198 that houses a fuel assemblycontroller 200, a bi-directional control and reporting interface 202, anoptional power interface 204 (shown in phantom), one or more memorymodules 206, a sensor interface 208, and an electronically controllablefuel handing system 210 coupled between to a fuel input connection 212and a fuel delivery interface 214.

According to one embodiment, fuel assembly controller 200 is a PLC ormicro-controller, along with associated memories, that provides controlelectronics for the electronic monitoring and reporting of memory module206 and fuel handing system 210. Fuel assembly controller 200 iselectrically connected to memory modules 206, fuel handing system 210,and bi-directional control interface 202 as shown in FIG. 7. Fuelassembly controller 200 may receive operating power from any number ofsources, including control and reporting interface 202, optional powerinterface 204, or other power source (not shown) such as an internalbattery or generator powered by fuel flow.

Fuel assembly manager 62 is also electrically coupled to and providescontrol electronics for the electrical monitoring and reporting of datareceived by sensor interface 208. Sensor interface 208 communicates witha fuel pressure sensor 216 and a fuel temperature sensor 218 mountedwithin housing 198 of fuel assembly manager 62.

In one embodiment, sensors 216, 218 are mounted within input fuelconnection 212 of fuel assembly manager 62. Sensor interface 208 alsocommunicates with one or more external sensor(s) 220 that are positionedexternal to fuel assembly manager 62 and mounted to pressure tank 60(FIG. 6). External sensor 220 is electrically coupled to fuel assemblymanager 62 using electrical connections 222. For each type of sensor216, 218, 220 fuel assembly controller 200 reads measurements fromsensors 216, 218, 220, optionally records them in memory module 206,reports them on the control and reporting interface 202, and/or takescontrol actions to manipulate the fuel handing system 210 in order tocontrol the flow of fuel. Although only three sensor inputs 216, 218,220 are shown for illustration, one skilled in the art will recognizethat fuel assembly manager 62 may interface with any number and type ofsensors as desired to monitor the contents of pressure tank 60, theoperation of fuel assembly manager 62, and the delivery of fuel fromfuel assembly 52. Using data acquired from sensor assembly and datastored on memory module 206, fuel assembly manager 62 can compute fueltank full data, based on input parameters, such as, for example,temperature, pressure, and tank size.

According to various embodiments, memory module 206 comprises any numberof non-volatile memories, either read-only or read-write, such as ROM orEEPROM, that are used to store information about the identity,capabilities, contents, and/or historical operations of fuel assembly52, as described below.

In one embodiment, memory module 206 includes a first tank memory 224that may include any of the following identifying information: anidentifier for fuel assembly 52 to uniquely identify fuel assembly 52,information describing capacity of pressure tank 60, informationdescribing construction of pressure tank 60, and information describingcapabilities of interchangeable gaseous fuel assembly 52, such as, forexample, temperature and pressure regulation capabilities. Additionally,first tank memory 224 may include identifying information regarding thehistory of interchangeable gaseous fuel assembly 52, includinginspection history and use history.

Memory module 206 may also include a second tank memory 226 that storesidentifying information about the fuel 166 currently stored in pressuretank 60 of the interchangeable gaseous fuel assembly 52. For example,second tank memory 226 may store identifying information about a currentfuel type (e.g., CNG, LNG, butane), fuel energy density, dateloaded/filled, fuel cost, and similar information related to the fuel166 within pressure tank 60.

Memory module 206 may further include a third tank memory 228 thatstores identifying information about the operational history ofinterchangeable gaseous fuel assembly 52, including historical sensorreadings (e.g., temperature and pressure over time), fill/dischargerates, operation of the fuel control system, and similar history ofoperating information for fuel assembly 52.

As shown in FIG. 7, fuel assembly controller 200 is electricallyconnected to tank control and reporting interface 202. According tovarious embodiments, control and reporting interface 202 is configuredto receive and transmit signals to and from fuel assembly controller 200to an external controller via an electrical connection with the externalcontroller and/or via the transmission of radio frequency signals.According to various embodiments, control and reporting interface 202may be configured to interface with an external controller such as aprimary locomotive controller, a controller coupled to an auxiliarypower unit, and/or controllers integrated into trackside equipment, asexamples. Control and reporting interface 202 may be connected to theexternal controller using physical connections, such as a CANbusconnection or an established locomotive control system interface. Thenature and type of control and reporting interface 202 may vary, as maythe number of control interfaces interfaced with, without departing fromthe design. In one embodiment, control and reporting interface 202 is anRF interface that permits memory module 206 of fuel assembly manager 62to be interrogated and optionally written to using RF-based technologiessuch as RFID. In such an embodiment, interface 202 is coupled to anoptional RIFD transmitter 230 (shown in phantom). This enables tracksideequipment, locomotive controllers, auxiliary power unit controllers, andthe like to interrogate memory module 206, and to write updatedinformation into the memory (such as new fuel type, energy density, andcosts) to the memory without requiring a physical connection to fuelassembly controller 200. Fuel assembly controller 200 responds torequests received by control and reporting interface 202 from externalcontrollers by configuring fuel handing system 210 to deliver fuel in arequested manner and/or reading or writing data to memory module 206.

Fuel assembly controller 200 is further connected to fuel handing system210 of fuel assembly manager 62. According to one embodiment, fuelhanding system 210 includes input fuel connection 212, an electronicallycontrollable valve 120, an optional expander/regulator 232 (shown inphantom), fuel delivery sensors 234, and a common fuel deliveryinterface 214. Input fuel connection 212 provides the connection pointfor fuel hose 184 at fuel input 186 of fuel assembly manager 62. In oneembodiment, input fuel connection 212 includes one or more industrystandard connectors, as well as any desired safety devices such as fuelshutoff and flow management devices for operation of interchangeablegaseous fuel assembly 52. Input fuel connection 212 is fluidly connectedto controllable valve 120, which is operated under the control of fuelassembly controller 200. Electronically controllable valve 120 mayinclude one or more solenoid controlled valves that can be used tocontrol the flow of fuel from pressure tank 60 to the common fueldelivery interface 214. In some embodiments, optional expander/regulatorequipment 232 such as fuel expanders (e.g., LNG warmers) and regulatorsmay be placed inline between controllable valve 120 and fuel deliveryinterface 214 to selectively heat and/or expand the fuel. Fuel assemblycontroller 200 is configured to regulate operation of electronicallycontrollable valve 120 to control whether fuel is passed throughexpander/regulator equipment 232 before being routed to the common fueldelivery interface 214.

Fuel assembly manager 62 is configured to manage the delivery of fuelunder relatively stable temperature and pressures, without regard to thestate of the fuel in pressure tank 60. For example, if fuel assemblymanager 62 receives a request to deliver fuel at two bar of pressure,and the fuel 166 within pressure tank 60 is liquid natural gas (LNG),fuel assembly controller 200 will cause fuel 166 to be warmed andexpanded to gaseous state at two bar within fuel assembly manager 62, sothat it may be delivered via the common fuel delivery interface 214 tothe given power unit. The controller-managed capabilities of fuelassembly manager 62 permits the interchangeable gaseous fuel assembly 52to seamlessly interoperate with various types of locomotive engines orpower units and deliver fuel and provide fuel to these various types ofunits at various temperatures and pressures.

After the gaseous fuel is in a state for delivery, it is routed past oneor more fuel delivery sensors 234 to the common fuel delivery interface214. Fuel delivery sensors 234 read the delivery parameters of the fuel(such as temperature, pressure, and flow rates) and transmit thesereadings to fuel assembly controller 200 to be recorded. According toone embodiment, fuel delivery interface 214 is a GMV-09 receptacle. Inone embodiment, fuel delivery sensor 234 measures a volume of fueldischarged from pressure tank 60.

Referring now to FIG. 8, in accordance with an alternative embodiment ofthe invention, fuel assembly 52 includes multiple pressure tanks 60connected together to form a pressure tank assembly 236. As shown,pressure tanks 60 are connected to a common manifold 238 by way ofrespective valves 240, which control access of each tank 60 to manifold238. Valves 240 may comprise any combination of manifold-specific flowmanagement devices such as shutoff valves, check values, and pressurerelease valves, for example. External sensors 220 are coupled torespective pressure tanks 60 via control cables (not shown) similar toelectrical connections 222 (FIG. 7) to monitor operating characteristicsof each tank 60, as explained in detail above. External sensors 220 andvalves 240 are electrically coupled to fuel assembly controller 200(FIG. 7) of fuel assembly manager 62 to control operations of andinteractions between pressure tanks 60. In embodiments where fuelassembly 52 includes multiple pressure tanks 60, memory module 206 offuel assembly manager 62 stores unique identifying information for eachpressure tank 60 within pressure tank assembly 236.

According to various embodiments, fuel assembly 52 is constructed toconform to a common size advantageous for transport throughout thelocomotive industry. In addition to enabling the interchange of thegaseous fuel assemblies, manufacturing interchangeable gaseous fuelassemblies in common sizes provide advantages in the transport of thefuel assemblies when they are not mounted on a locomotive or railcar. Inone embodiment, fuel assembly 52 is sized to correspond to the size ofan intermodal container. As used herein, the term “intermodal container”refers to a container specifically designed for transport by rail, roadtruck, and ship with standardized sizing and features for accommodatinguse in each such mode of transportation. Particularly advantageous aresizes that correspond to the smaller intermodal container sizes, suchas, for example, a container having a length of approximately 10 feet,20 feet, 30 feet, or 40 feet, a height of approximately four foot sixinches, eight feet six inches, or nine feet six inches, and a width ofapproximately eight feet, although one skilled in the art will recognizethat other sizes may be suitable depending upon the particularembodiment. According to an exemplary embodiment, frame 152 of fuelassembly 52 is sized to correspond to an intermodal container having alength of 20 feet, a height of eight feet six inches, and a width ofeight feet.

Fuel assembly 52 delivers several important advantages when used inrailroad operations. First, fuel assembly 52 enables rapid refueling ofrailroad power generation equipment without the use of expensiveyard-based lift equipment. Second, fuel assembly 52 enables the use ofvarious types of gaseous fuels, depending upon what fuels are locallyavailable. Third, fuel assembly 52 interfaces with power generation andlocomotive power control systems to enable these systems to optimize orat least improve their use and cost of power.

Referring now to FIG. 8, a gaseous fuel locomotive 242 is illustratedthat incorporates fuel assembly 52 of FIG. 6. While fuel assembly 52 isillustrated in FIG. 8 as including a single pressure tank 60, oneskilled in the art will recognize that fuel assembly 52 mayalternatively be configured with a multiple pressure tank assembly 236,as described with respect to FIG. 7. Gaseous fuel locomotive 242includes one or more genset engines 118 configured to burn gaseous fuelsand a control system 244 that controls the operation of the gensetengines 118. Gaseous fuel locomotive 242 may be designed for line haulor switching use, according to various embodiments.

Interchangeable gaseous fuel assembly 52 is fastened to the locomotiveframe 246 using connecting pins (not shown) fastened to corner fittings164 (FIG. 6) on fuel assembly 52 and to corresponding fittings (notshown) on locomotive frame 246. These pin/fitting combinations permitoperations workers to removably secure gaseous fuel assembly 52 to alocomotive frame 246. The pin assembly also provides a groundedconnection between gaseous fuel assembly 52 and locomotive frame 246.

Gaseous fuel assembly 52 is further connected to locomotive 242 using acontrol interconnection cable 248, which electrically connects fuelassembly manager 62 of fuel assembly 52 to the locomotive's controlsystem 244. The control system 244 has been configured or adapted torecognize and manage gaseous fuel assembly 52. Specifically, the controlsystem 244 is configured to recognize one or more of: (a) that a gaseousfuel assembly 52 is present, (b) the type of fuel gaseous fuel assembly52, (c) the energy density of the fuel within gaseous fuel assembly 52,and (d) the cost of the fuel in gaseous fuel assembly 52, as describedin more detail below.

Gaseous fuel assembly 52 is further connected to locomotive 242 using aremovable gaseous fuel line 250 that mates with fuel delivery interface214 of fuel assembly 52 and with a similar fuel interface 252 on gaseousfuel locomotive 242. As shown, fuel interface 252 is fluidly connectedto genset engines 118 on gaseous fuel locomotive 242.

According to one embodiment, gaseous fuel assembly 52 receives auxiliarypower from an auxiliary power bus (not shown) of gaseous fuel locomotive242. The auxiliary power received from auxiliary power bus may be usedto power expander/regulator 232 of fuel assembly manager 62 in order toconvert a fuel within pressure tank 60 such as, for example, LNG to adesired gaseous state for delivery to locomotive 242.

Although only one interchangeable gaseous fuel assembly 52 is shown inFIG. 8, a locomotive configured or adapted for use with interchangeablegaseous fuel assemblies may utilize more than one interchangeablegaseous fuel assembly 52 to extend the operating range of the gaseousfuel locomotive 242. One benefit of the interchangeable gaseous fuelassemblies 52 is that they allow a locomotive to use fuels withdiffering storage requirements (e.g., LNG vs. CNG) without anyadaptation of the locomotive itself. Thus, interchangeable gaseous fuelassemblies 52 allow the use of common designed gaseous fuel locomotivesthat can use whatever gaseous fuel best meets the required energydensity and capacities for the operating conditions. The same fuelstructure can be used for CNG and the more energy-dense LNG.Alternatively, the locomotive can operate on whatever gaseous fuel isavailable, such as syngas or process gases, by simply changing theinterchangeable gaseous fuel assembly 52.

In addition to enabling locomotive 242 to operate on whatever gaseousfuel best fits current operational parameters, the use of fuel assemblymounted on locomotive frame 246 provides significant operationaladvantages. For example, the interchangeability of gaseous fuel assemblypermits fast servicing and refueling of locomotive 242. Traditionalgaseous fuel tanks require very long recharge times (on the order ofeight hours) to completely recharge when coupled to an economicallyselected compression unit. Alternatively, to rapidly fill frompre-stored compressed gas tanks requires a considerably larger volume oftanks in the refilling system and/or higher pressures for those tanksGaseous fuel assembly, on the other hand, may be swapped with anothergaseous fuel assembly in a much shorter time frame (e.g., less thanfifteen minutes) than the typical times associated with high pressurediesel refueling.

In addition, gaseous fuel assembly 52 can be changed trackside withoutoverhead rail yard-based equipment such as lift gantries, which can liftcontainers with weights up to approximately 40,000 pounds. Gaseous fuelassembly 52 is also constructed to be below a maximum weight capacity ofa truck-mounted crane or forklift to permit trackside interchange ofgaseous fuel assembly 52. Depending upon the specific truck-mountedcrane, the lifting capacity is limited to appropriately 10,000 or 20,000pounds in one embodiment. These operational features of gaseous fuelassembly 52 support the railroad industry's “just in time” fuelinginitiatives, where fuel meets the train during crew changes instead ofthe train refueling at fixed stops.

In operation, control system 244 of gaseous fuel locomotive 242communicates with fuel assembly manager 62 of fuel assembly 52 todetermine identifying information for fuel assembly 52. Based on thereceived identifying information, control system 244 may, for example,identify a type of fuel within fuel assembly 52 and transmit controlcommands to fuel assembly manager 62 to deliver fuel to locomotive 242at a desired pressure and/or temperature. Control system 244 of gaseousfuel locomotive 242 may be further configured to selectively adjustcommand signals sent to genset engines 118 based on the identified typeof fuel.

As set forth above, the improved locomotive controller and thealternative power and fuel systems described herein permit thelocomotive operator to manage their power production to a specific costby blending power from multiple power sources using a variety of fuels.

A technical contribution for the disclosed method and apparatus is thatit provides for a computer implemented control of an auxiliaryengine-generator set and one or more engine-generator sets of alocomotive. One or more auxiliary engine-generator sets are controlledto produce a desired amount of power and deliver power to a power bus. Acombination of one or more auxiliary engine-generator sets and one ormore locomotive engine-generator sets are controlled to provide power inaccordance with a power allocation.

One skilled in the art will appreciate that embodiments of the inventionmay be interfaced to and controlled by a computer readable storagemedium having stored thereon a computer program. The computer readablestorage medium includes a plurality of components such as one or more ofelectronic components, hardware components, and/or computer softwarecomponents. These components may include one or more computer readablestorage media that generally stores instructions such as software,firmware and/or assembly language for performing one or more portions ofone or more implementations or embodiments of a sequence. These computerreadable storage media are generally non-transitory and/or tangible.Examples of such a computer readable storage medium include a recordabledata storage medium of a computer and/or storage device. The computerreadable storage media may employ, for example, one or more of amagnetic, electrical, optical, biological, and/or atomic data storagemedium. Further, such media may take the form of, for example, floppydisks, magnetic tapes, CD-ROMs, DVD-ROMs, hard disk drives, and/orelectronic memory. Other forms of non-transitory and/or tangiblecomputer readable storage media not list may be employed withembodiments of the invention.

A number of such components can be combined or divided in animplementation of a system. Further, such components may include a setand/or series of computer instructions written in or implemented withany of a number of programming languages, as will be appreciated bythose skilled in the art. In addition, other forms of computer readablemedia such as a carrier wave may be employed to embody a computer datasignal representing a sequence of instructions that when executed by oneor more computers causes the one or more computers to perform one ormore portions of one or more implementations or embodiments of asequence.

Therefore, according to one embodiment of the invention, an auxiliarypower unit assembly for a locomotive includes an auxiliary power unitremovably coupleable to a rail car chassis. The auxiliary power unitincludes a housing, and an auxiliary engine-generator set positionedwithin the housing. The auxiliary engine-generator set is configured toprovide an auxiliary power to the locomotive. The auxiliary power unitalso includes an auxiliary controller electrically coupled to theauxiliary engine-generator set. The auxiliary controller is programmedto receive a command and control at least one aspect of the auxiliarypower unit in response to the command.

According to another embodiment of the invention, a locomotive assemblyincludes a locomotive having a power bus, a primary engine-generator setelectrically coupled to the power bus, and a locomotive controllerprogrammed to control the primary engine-generator set. The locomotiveassembly further includes a first power unit having a first auxiliaryengine-generator set electrically coupled to the locomotive power busand a first auxiliary controller. The first auxiliary controller isprogrammed to receive a command signal from the locomotive controllerindicating a desired amount of power, and control the first auxiliaryengine-generator set to produce the desired amount of power.

According to yet another embodiment of the invention, a method ofproviding auxiliary power by an auxiliary power unit includes couplingthe auxiliary power unit to a power bus of the locomotive, where theauxiliary power unit includes an auxiliary engine-generator set and anauxiliary controller electrically coupled to the auxiliaryengine-generator set. The method also includes coupling the auxiliarycontroller to a primary locomotive controller, receiving a power commandfrom the primary locomotive controller in the auxiliary controller, andcontrolling the auxiliary engine-generator set to generate an auxiliarypower for delivery to a power bus of the locomotive responsive to thepower command.

According to embodiments of the invention, the locomotive controller isprogrammed to determine the desired amount of power based on operatingcosts of the first auxiliary engine-generator set versus that of theprimary engine-generator set. In one embodiment, the locomotivecontroller is programmed to transmit a command signal to the APU thatincludes one of a desired operating point on a performance graph of thefirst auxiliary power unit and a desired power level of the output powerof the first auxiliary power unit.

The identified operating parameters of the first power unit include atleast one of an equipment configuration of the first auxiliary powerunit, performance characteristics of the first auxiliary power unit,operational history data of the first auxiliary power unit, and acurrent status of the first auxiliary power unit.

According to embodiments of the invention, a locomotive assemblyincludes a locomotive, a first power unit and a second power unit. Eachpower unit includes a respective auxiliary engine-generator setelectrically coupled to the power bus; and a respective auxiliarycontroller programmed to receive a command signal from the locomotivecontroller indicating a desired amount of power; and control itsrespective auxiliary engine-generator set to output the desired amountof power. According to embodiments of the invention, the locomotivecontroller is further programmed to identify operating parameters of thefirst power unit, identify operating parameters of the second powerunit, determine a desired amount of power from the first power unitbased on the identified operating parameters of the first power unit,determine a desired amount of power from the second power unit based onthe identified operating parameters of the second power unit, transmit afirst command signal to the first auxiliary controller indicating thedesired amount of power from the first power unit, and transmit a secondcommand signal to the second auxiliary controller indicating the desiredamount of power from the second power unit.

According to embodiments of the invention, the auxiliary power unitassembly includes an auxiliary power unit removably coupleable to a railcar chassis. The auxiliary power unit includes a housing; anengine-generator set positioned within the housing, the engine-generatorset configured to provide an auxiliary power to the locomotive; and anauxiliary controller electrically coupled to the engine-generator set.The auxiliary controller is programmed to receive a command and controlat least one aspect of the power unit in response to the command. Theauxiliary controller includes a controller memory that storesidentifying information for the auxiliary power unit. The identifyinginformation may include, for example, a power unit identification, powerunit operational parameters, and/or power unit operational historyinformation. According to embodiments of the invention, the auxiliarycontroller the controller memory is a volatile memory (register).According to various embodiments, the controller is programmed toperform one or more of the following actions: identify when the APU isconnected to another device on a control interface, identify when theAPU is connected to another device on a power interface, and identifywhen the APU is connected to a fuel assembly on a fuel assemblyinterface.

According to various embodiments, the APU controller is furtherprogrammed to identify when the APU is newly connected to another deviceon the control interface and take a control action, such as, forexample, identify characteristics of the newly connected device, andprovide notification to the newly connected device, the notificationincluding providing identifying information for the APU. The APUcontroller is further programmed to identify when the APU isdisconnected from a previously connected device on the controlinterface, and to take a disconnection action, such as, for example,recalculating parameters dependent upon the device, providingnotification of the disconnect to other connected devices, and providingnotification of recalculated parameters to connected devices.

According to various embodiments, the APU controller is furtherprogrammed to identify when the APU is newly connected to another deviceon the power interface and take a power action selected from a set ofconnection on power actions, similar to the connection actions describedabove. The APU controller is further programmed to identify when the APUis disconnected from another device on the power interface and take apower action selected from a set of disconnection on power actions,similar to the disconnection actions described above. The APU controlleris further programmed to initiate a shutdown protocol upon detection ofa fault, wherein the APU controller shunts the first auxiliaryengine-generator set.

According to various embodiments, the APU controller is furtherprogrammed to identify when the APU is newly connected to a fuelassembly interface and take an action selected from a set of connectionof fuel assembly actions, similar to the connection actions describedabove. The APU controller is further programmed to identify when the APUis disconnected from a previously connected fuel assembly on the fuelassembly interface and take an action selected from a set ofdisconnection of fuel assembly actions, similar to the disconnectionactions described above.

According to various embodiments, the APU controller is furtherprogrammed to recognize a fault presented on its common interface, andto take independent action to control at least one aspect of theoperation of the APU selected from the a set of fault response actions.The fault response actions may include, for example, disconnect the APUfrom the power bus, send a message on the control interface, change theengine-generator settings, change a fuel valve setting, record the faultin a memory, and change the amount of power delivered by a powerinterface. The APU controller may be further programmed to recognize afault reported by a sensor or fault detection apparatus, recognize afault presented on its common interface, recognize a fault of itsengine/generator assembly, recognize a mechanical fault from amechanical fault sensor, recognize a fault with a fuel assembly,recognize a control cable connection/disconnection, and/or recognize apower cable connection/disconnection, and to take independent action tocontrol at least one aspect of the operation of the APU selected fromthe set of fault response actions listed above.

According to embodiments of the invention, the auxiliary power unitassembly includes circuitry to identify signal degradation of controlsignals received by the auxiliary power unit. The circuitry isconfigured to generate an adjusted control signal based on theidentified signal degradation, and transmit the adjusted control signalto the auxiliary power unit. According to one embodiment, the auxiliarypower unit assembly also includes input characteristic conversioncircuitry configured to change the characteristics of the input signalso as to provide a valid control input to the auxiliary power unit. Theinput character conversion circuitry translates from an interferenceresistant transmission format to a format usable by the auxiliarycontroller; translates an engine control signal to a differing enginecontrol signal; and translates an engine control signal to a powercommand.

Embodiments of the invention include an auxiliary fuel supply fluidlycoupled to the auxiliary engine-generator set. In one embodiment, thefirst power unit and the auxiliary fuel supply are located on tender carseparate from the locomotive. In one embodiment, the fuel assembly isstacked atop the housing of the auxiliary power unit.

According to one embodiment of the invention, a power connection cableis electrically coupled between the output of the first auxiliaryengine-generator set and the locomotive power bus; and a disconnectsensor coupled to the power connection cable, the disconnect sensorconfigured to sense a connection status of the first auxiliaryengine-generator set with the power bus. The first auxiliary controlleris programmed to receive an alert signal from the disconnect sensorindicating a disconnection between the power connection cable and thepower bus, and upon receiving the alert signal, initiate a shutdownprotocol for the first auxiliary engine-generator set.

According to another embodiment of the invention, a control connectioncable is electrically coupled between the primary locomotive controllerand the first auxiliary controller. At least one of the primarylocomotive controller and the first auxiliary controller is furtherprogrammed to detect a fault in the transmission of control commandsthrough the control connection cable. Upon detection of the fault, theprimary locomotive controller is programmed to perform at least one ofthe following actions: resend the power command, modify the powercommand, transmit a signal to the primary locomotive controllerindicating a disconnect fault.

According to one embodiment of the invention a method of providingauxiliary power to a locomotive includes coupling an auxiliary powerunit to a power bus of the locomotive. The auxiliary power unit includesan auxiliary engine-generator set and an auxiliary controllerelectrically coupled to the auxiliary engine-generator set. The methodfurther includes coupling the auxiliary controller to a primarylocomotive controller, receiving a power command from the primarylocomotive controller in an auxiliary controller, and controlling theauxiliary engine-generator set to generate an auxiliary power fordelivery to the power bus responsive to the power command. The methodalso includes identifying the auxiliary power unit, generating a powercommand specific to the identified auxiliary power unit, andtransmitting the power command to the auxiliary controller. The methodfurther includes coupling an auxiliary fuel supply to the auxiliarypower unit, detecting at least one of a cost of fuel and a type of fuelin the auxiliary fuel supply, and controlling the auxiliary controllerto regulate operation of the auxiliary engine-generator set based on thedetected type of fuel and/or cost of fuel in the auxiliary fuel supply.The method of providing auxiliary power to a locomotive also includesboosting the power command to account for a voltage drop in the powercommand between the primary locomotive controller and the auxiliarycontroller. The method also includes detecting a decoupling eventbetween the auxiliary power unit and the power bus and shunting theauxiliary engine-generator set within a short amount of time, such as,for example, 10 milliseconds, upon detection of the decoupling event.The method also includes blending power from the auxiliary power unitand the locomotive on the power bus. In some embodiments, the methodincludes blending power from multiple auxiliary power units on the powerbus.

According to one embodiment of the invention, a power car or auxiliarypower unit is connected to a plurality of locomotives, and providespower to each locomotive independently of the other. In an alternativeembodiment, a plurality of power cars are connected to a locomotive, andeach power car provides power to the locomotive. In an alternativeembodiment, a power car is connected to a plurality of locomotives, andthe power car receives requests and sends responses independently toeach of the locomotives. In yet another embodiment, a power car isconnected to a plurality of locomotives, the power car receives powerrequests from each locomotive independently, combines the requests to asingle power requirement, determines the power settings of anengine-generator of the power car effective to produce power for the sumof the requests, configures the power interfaces to deliver power fromthe engine-generator in accordance with the request.

While the invention has been described in detail in connection with onlya limited number of embodiments, it should be readily understood thatthe invention is not limited to such disclosed embodiments. Rather, theinvention can be modified to incorporate any number of variations,alterations, substitutions or equivalent arrangements not heretoforedescribed, but which are commensurate with the spirit and scope of theinvention. Additionally, while various embodiments of the invention havebeen described, it is to be understood that aspects of the invention mayinclude only some of the described embodiments.

Accordingly, the invention is not to be seen as limited by the foregoingdescription. The patentable scope of the invention is defined by theclaims, and may include other examples that occur to those skilled inthe art. Such other examples are intended to be within the scope of theclaims if they have structural elements that do not differ from theliteral language of the claims, or if they include equivalent structuralelements with insubstantial differences from the literal languages ofthe claims.

What is claimed is:
 1. An auxiliary power unit assembly for a locomotivecomprising: an auxiliary power unit removably coupleable to a rail carchassis, the auxiliary power unit comprising: a housing; and anauxiliary engine-generator set positioned within the housing, theauxiliary engine-generator set configured to provide an auxiliary powerto the locomotive; and an auxiliary controller electrically coupled tothe auxiliary engine-generator set, the auxiliary controller programmedto: receive a command; and control at least one aspect of the auxiliarypower unit in response to the command.
 2. The auxiliary power unitassembly of claim 1 wherein the auxiliary controller is furtherprogrammed to provide a response signal on a control interface of theauxiliary power unit.
 3. The auxiliary power unit assembly of claim 1wherein the auxiliary controller is further programmed to determine apower setting corresponding to an amount of power provided by theauxiliary power unit to a locomotive power bus.
 4. The auxiliary powerunit assembly of claim 3 wherein the auxiliary controller is furtherprogrammed to set the amount of power to the locomotive power buswithout changing the configuration of the auxiliary engine-generatorset.
 5. The auxiliary power unit assembly of claim 1 wherein theauxiliary controller is further programmed to control the auxiliarypower unit to configure the auxiliary engine-generator set to produce aselected amount of power.
 6. The auxiliary power unit assembly of claim1 wherein the auxiliary controller is further programmed to communicatewith one or more fuel sources fluidly coupled to the auxiliary powerunit.
 7. The auxiliary power unit assembly of claim 1 further comprisinga fault sensor electrically coupled to the auxiliary controller; andwherein the fault sensor is configured to monitor at least one of acontrol input, a power input, an operation of the auxiliaryengine-generator set, a fuel subsystem, one or more fuel tanks, and oneor more operational aspects of the auxiliary power unit.
 8. Theauxiliary power unit assembly of claim 1 wherein the auxiliarycontroller is further programmed to: identify an amount of signaldegradation in the command based on a length of travel of the commandbetween the primary locomotive controller and the auxiliary controller;adjust the command to account for the identified signal degradation; andselectively control the auxiliary engine-generator set based on theadjusted command.
 9. The auxiliary power unit assembly of claim 1further comprising: a plurality of independently controllable powercables coupleable to a power bus; a power sensor operably connected tothe power cables and the auxiliary controller; a meter operablyconnected to the power cables and the auxiliary controller, the meterconfigured to measure an amount of power transferred over the powercables; a power regulator operably connected to the power cables and theauxiliary controller effective to regulate the amount of power output tothe power bus; and a switch operably connected to the power cables andthe auxiliary controller effective to logically disconnect the powerunit from the output power bus.
 10. The auxiliary power unit assembly ofclaim 1 wherein the auxiliary controller comprises one of an autonomousdigital controller and an autonomous analog controller; and wherein theauxiliary controller operates independently.
 11. The auxiliary powerunit assembly of claim 1 further comprising at least one fuel assemblyfluidly coupled to the auxiliary power unit, the at least one fuelassembly comprising: at least one removable gaseous fuel supply; a valvesystem fluidly coupling the removable gaseous fuel supply to theauxiliary engine-generator set; and wherein the auxiliary controller isfurther programmed to: identify characteristics of the removable gaseousfuel supply; and regulate operation of the auxiliary engine-generatorset based on the identified characteristics of the removable gaseousfuel supply.
 12. The auxiliary power unit assembly of claim 1 whereinthe auxiliary controller is further programmed to: store identifyinginformation for the auxiliary power unit assembly, the identifyinginformation comprising at least one of performance information of theauxiliary power unit, an equipment configuration of the auxiliary powerunit, operational history of the auxiliary power unit, and a currentstatus of the auxiliary power unit; and periodically transmit theidentification information on a control interface of the auxiliary powerunit at predefined time intervals.
 13. The auxiliary power unit assemblyof claim 1 wherein the auxiliary controller is further programmed to:receive a fault indication from a fault sensor; and respond to the faultindication by taking at least one of the following actions: disconnectthe auxiliary power unit from a power bus, send a message on a controlinterface, change settings of the auxiliary engine-generator, change afuel valve setting, and record the fault indication in a memory.
 14. Anauxiliary power unit assembly for a locomotive comprising: an auxiliarypower unit removably coupleable to a rail car chassis, the auxiliarypower unit comprising: a housing; and an auxiliary engine-generator setpositioned within the housing, the auxiliary engine-generator setconfigured to provide an auxiliary power to the locomotive; and anauxiliary controller electrically coupled to the engine-generator set,the auxiliary controller programmed to: receive an engine controlsetting; transform the engine control setting to a power command; andselectively control the auxiliary engine-generator set to produce adesired amount of power responsive to the received power command. 15.The auxiliary power unit of claim 14 wherein the auxiliary controller isfurther programmed to: receive the power command from a primarylocomotive controller; and control power production by the auxiliaryengine-generator set to cooperate with power produced by the locomotive.16. A locomotive assembly comprising: a locomotive comprising: a powerbus; a primary engine-generator set electrically coupled to the powerbus; and a locomotive controller programmed to control the primaryengine-generator set; and a first power unit comprising: a firstauxiliary engine-generator set electrically coupled to the locomotivepower bus; and a first auxiliary controller programmed to: receive acommand signal from the locomotive controller indicating a desiredamount of power; and control the first auxiliary engine-generator set toproduce the desired amount of power.
 17. The locomotive assembly ofclaim 16 wherein at least one of the locomotive controller and the firstauxiliary controller are further programmed to determine a connectionstatus of the first power unit to the power bus.
 18. The locomotiveassembly of claim 16 wherein the locomotive controller is furtherprogrammed to: identify operating parameters of the first power unit;and determine a desired amount of power from the first power unit basedon the identified operating parameters of the first power unit; andtransmit the command signal to the first auxiliary controller indicatingthe desired amount of power.
 19. A method of providing auxiliary powerby an auxiliary power unit, the method comprising: coupling theauxiliary power unit to a power bus of the locomotive, the auxiliarypower unit comprising an auxiliary engine-generator set and an auxiliarycontroller electrically coupled to the auxiliary engine-generator set;coupling the auxiliary controller to a primary locomotive controller;receiving a power command from the primary locomotive controller in theauxiliary controller; and controlling the auxiliary engine-generator setto generate an auxiliary power for delivery to a power bus of thelocomotive responsive to the power command.